JVIB Copyright 2010 American Foundation for the Blind. All rights reserved.
File created April 10, 2010. This is not the final version of record. The
following article was published in the Journal of Visual Impairment &
Blindness, April 2010 • Volume 104 • Number 4, (Print edition pages 203-214). The final version of record can be found
JVIB - April, 2010
Teaching the Use of a Long Cane Step by Step:
Suggestions for Progressive, Methodical Instruction
Dona Sauerburger and Eugene Bourquin
Abstract: A fundamental part of the orientation and mobility curriculum is the acquisition and retention of skills in using a long cane automatically and proficiently to detect and negotiate obstacles and drop-offs. Using practitioners' experiences and the principles of learning theory, instructors can monitor students' advancement and adapt teaching strategies to optimize the results.
One of the important skills of orientation and mobility (O&M) instruction is the use of the long cane for anticipating what is ahead of the user and negotiating obstacles and changes in surface elevation (such as steps and curbs). However, use of the cane will not ensure the safety of students unless they reach a sufficient level of proficiency in the skills of moving the cane correctly without having to concentrate, being able to notice unexpected obstacles and steps even when distracted, and knowing how to negotiate obstacles and steps safely.
For example, a man who learned how to use a cane fell off a curb because he was not able to move the cane correctly when distracted. A woman who could move the cane well even when distracted fell off a transit platform because she did not notice when the cane went over the edge. An intern at a nursing home who was proficient with the cane had not learned how to negotiate obstacles, so she knocked over a patient because she sidestepped to get around a medicine cart she had contacted with her cane. These people all needed further instruction and practice before their ability to use the cane to notice and negotiate hazards was proficient enough to provide for their safety. This article presents ideas and information that may help facilitate instruction in and practice with using a cane, drawn from extended observations in professional practice and the results of research from physical therapy, neuroscience, and psychology.
Appropriate practice and instruction
According to Ackerman (2007, p. 238), "Although practice is the primary determinant of individual differences in skilled performance of tasks with significant motor requirements, the sheer amount of practice provides only a moderate amount of explanatory power." Practice can be made more efficient with careful consideration of the principles of learning.
Students go through a series of stages as they learn any skill, and instruction should vary according to the stage of learning. For example, the beginning stages of learning require the student to concentrate on the task, whereas advanced students can perform the task with little or no effort (psychologists call this "autonomous performance"; Ackerman, 2007, p. 236). According to Adi-Japha, Karni, Parnes, Loewenschuss, and Vakil (2008, p. 1544), improvements in performance "are related to transitions between two types of processing modes: an initial, controlled, more effortful mode and eventually a more automatic mode."
In 1911, mathematician Whitehead noted:
It is a profoundly erroneous truism, repeated by all copy-books and by eminent people when they are making speeches, that we should cultivate the habit of thinking of what we are doing. The precise opposite is the case. Civilization advances by extending the number of important operations which we can perform without thinking about them. (p. 61)
Likewise, it is an advantage to students with visual impairments to reach a level of proficiency where they do not have to "think" about their canes or the details of the techniques they are using but, rather, perform in a manner that is independent of cognitive control. Some aspects of successful travel, such as learning to use landmarks in the environment for traveling routes, require conscious cognitive effort (Martinsen, Tellevik, Elmerskog, & Storlilokken, 2007); we suggest that effective use of a cane need not be one of these components that require such cognitive effort.
Retention of skills is the goal of practice, as described by Maas et al. (2008, p. 278): "The distinction between performance during acquisition (practice) and retention or transfer implies that learning, a permanent change in the capability of skilled movement, must be measured by retention and/or transfer tests. Retention refers to performance levels after the completion of practice." For cane skills, which are motor related, the student will follow through the acquisition and retention stages; note, however, that learning how to negotiate obstacles can be done at any time, even when the student is in the beginning stages of learning to use a cane.
The retention of skills depends on temporal factors, including the human sleep cycle. Studies have shown that after practicing a task and undergoing another practice session "between 10 minutes and 6 hours later, without intervening sleep, the memory undergoes the first, stabilization phase of consolidation, making it resistant to interference from a competing memory" (Walker, Brakefield, Hobson, & Stickgold, 2003, p. 618). However, even though spacing practice sessions apart can help consolidate the skill memory, it does not necessarily improve speed or accuracy for performance. In experiments published in 2003, Walker et al. reported that "following practice of a specific motor sequence, delayed performance improvements only occur across a night of sleep [emphasis added], while waking periods of 4, 8 or even 12 hours offer no such performance enhancements" (p. 617). An awareness of timing and scheduling for practice can be used in each stage of cane mastery.
The practice of cane techniques can also be maximized with appropriate feedback from the instructor. Studies have consistently shown that too much feedback can impede learning. Sullivan, Kantak, and Burtner (2008) found that when participants received feedback on their performance only 62% of the time, beginning with frequent input and fading to less input, they performed motor skills more consistently and accurately when tested later, as opposed to those who always received feedback. The authors hypothesized that "educed feedback practice conditions … increase information-processing demands during practice that are advantageous to the relatively permanent effects associated with motor learning observed in a delayed retention test" (p. 721). Jacobson and Bradley (1997) also suggested that after providing continuous reinforcement in the beginning of instruction, providing less frequent praise later will encourage a student to continue to engage in high levels of effort. Instructors should monitor and consider the amount and timing of the correction and input they provide as students pass through the stages of acquiring cane skills.
Stages of learning
It may be helpful to understand what expectations and teaching strategies could be appropriate as students move through the various phases of acquiring cane skills. We propose, on the basis of the results of empirical studies (Walker et al., 2003; Sullivan et al., 2008), the following model of how students pass through stages of learning to use a cane:
Stage 1: Beginner--acquiring manual performance skills. The student is learning how to move the cane and requires feedback and correction.
Stage 2: Concentration--maintaining independent movement. The student can maintain the correct cane technique without correction but only with concentration.
Stage 3: Consolidation--performance without concentration. The student can maintain the correct cane technique without conscious concentration; movement of the cane has become natural for the student and is done correctly even when the student is distracted. However, the student may not notice when the cane drops over an edge that was not expected.
Stage 4: Proficiency--noticing and using information provided by the cane. The student moves the cane correctly without having to concentrate and notices when the cane contacts any unexpected edges or obstacles even when the ground seems flat. At this stage, the cane provides the student with a reliable warning of hazards in all situations (see Box 1).
BOX 1: Obstacles that a cane may not detect
Students should be aware that the cane cannot always protect them from
1. overhanging obstacles, such as tree branches and protruding signs;
2. objects and holes that are small or low enough that the cane can go around them; and
3. poles and corners that the cane tip can go around.
The shaft of the cane will, however, contact these objects if they are close enough to where the hand holding the cane is approaching, which means that the head is protected if the hand is centered in front of the body.
In the first stage of learning to use a cane, the student learns the mechanics of moving it correctly. Moving the cane correctly involves several skills (maintaining the correct hand position and movement and the correct arc of the cane tip, moving the cane in rhythm with the feet, and staying in step). Feedback from the instructor can be frequent at the beginning and fade out as the student improves.
Because the first and second stages of learning require students' full concentration, students in these stages need a sufficient amount of time to practice without having to perform other tasks simultaneously, such as noticing sensory information or finding destinations. The goal is for the student to establish muscle memory until using a long cane "becomes increasingly resistant to interference from competing or disrupting factors with the continued passage of time" (Walker et al., 2003, p. 616). As Jacobson (1993) explains, "Motor skills need to become ingrained before students can be expected to concentrate on higher-level orientation skills" (p. 12).
To prevent tedium and improve the quality and quantity of skills that are acquired, practice can be interrupted with activities to work on skills and concepts that are dissimilar, such as how to negotiate obstacles or locate dropped objects, or to develop students' kinesthetic sense or echolocation skills. The instructor should also be aware that pacing practice of similar skills is critical for long-term retention. The term massed practice refers to rehearsal without intermittent pauses, as opposed to distributed practice, which is rehearsal with breaks. Schilling, Marangoni, Vidal, and Rajan (2000, p. 3) claimed, "Abundant research indicates that distributed practice improves learning rates over massed practice, presumably because it gives the learner time to do the kind of deep, elaborative processing that enables development of the knowledge structures." By using a distributed schedule for learning, O&M specialists can effectively relieve boredom that is associated with repetitive tasks and provide students with time to recoup and reflect on the instruction.
With the exception of the skill of maintaining rhythm, it may be helpful to isolate one skill at a time until the student can at least demonstrate it correctly and then add other skills later. As Walker et al. (2003, p. 617) demonstrated, instruction in more than one similar task can impede acquisition. The phenomenon is called interference. Walker stated that "when subjects … were trained on a second motor sequence immediately after the first, interference was seen, so that overnight improvement in accuracy only occurred for the second sequence, and not the first" (p. 617). Instructors should be aware of the effect of interference; when they observe it, they can focus on a single skill or subset of a skill (such as hand position and movement of the cane) during that day's lesson and wait until another day to practice other skills (such as moving the cane in rhythm with the feet).
When students have difficulty learning the skill of maintaining the rhythm of the cane, the instructor can temporarily suspend work on skills they may have already mastered, such as arc and hand position, and work only on developing a sense of moving the cane in rhythm with the feet. Often students will acquire that sense of rhythm if the instructor moves the cane for them while they walk. If that strategy does not work, students may get the sense of moving something in rhythm with their feet by tapping their hand on their hip in time with their steps while the instructor guides them (with no cane) and then taps the cane in rhythm with their steps (ignoring the arc and hand position until they can gain a sense of what it feels like to move the cane in rhythm with their feet). Once they are able to coordinate the rhythm of the cane movement with that of their feet, they can work on moving the cane with the correct arc and hand position.
When students have mastered the correct cane technique and can maintain it without any prompting if they are concentrating, they are in the second stage of learning to use a cane. In this stage, students still need sufficient practice without interference because they still need to concentrate on the skill. Any distraction, such as a question or statement, may result in the student's cane technique deteriorating or cause the student to deviate from the correct technique. At one time, we thought it was simply coincidence that whenever we complemented students on their technique, they momentarily lost their ability to use the cane properly. Now we suspect that we were distracting the students during a period of their training in which they still needed to concentrate. The instructor's constant presence is not necessary in this stage, except perhaps to ask the students periodically to check themselves to see if they are in step.
By the end of the second stage, students do not walk out of step for long before they notice and automatically correct themselves because it just does not feel right to them. To determine whether students have passed through the second stage of learning and have achieved the third stage, the instructor may ask them a question while they are using the cane. If the students are still in the second stage, their cane technique will deteriorate while they ponder the question; for example, they will get out of step, the arc will shift to one side, or they may even stop walking.
The process of solidifying skills, known to neuroscientists as "consolidation" is achieved by the third stage of learning to use a cane. As Diekelmann and Born (2007, p. 1085) noted:
As with other types of memories, once skill memories (such as riding a bike) are acquired, they pass through a phase in which the newly encoded neuronal memory representation is labile, and thus vulnerable to disruption and interference. Building a memory that is remembered forever requires that memory traces be transformed into a robust, stable form that is resistant to disruption.
When students have achieved consolidation, their cane skills are stabilized to the point that they no longer have to concentrate to move the cane correctly and consistently. Students can be expected to maintain an effective cane technique while paying attention to sensory information and work on other tasks, such as orientation. Jacobson (1993) noted that when this stage is complete, motor skills become "second nature."
As students enter the third stage, execution of the cane technique may still occasionally falter if the cane tip jams, but this situation improves with practice. In this stage, students often need prompting or correcting soon after they first use the cane outside because the cane jams so often, but before long the technique remains consistent even in rough terrain.
Even though students in this stage move the cane correctly and consistently, many of them (especially those with functional vision) do not respond reliably to the information provided by the cane. They sometimes trip or fall on a stair or obstacle even when using the cane correctly because they continue to walk forward unaware that the cane has dropped over an edge or contacted an obstacle.
Therefore, when students have reached the third stage of learning to use a cane, the instructor needs to assess whether they can reliably and consistently notice and react to the information that the cane provides about drop-offs and obstacles, even when the students are distracted. Individuals who have functional vision must be assessed to be sure they can reliably notice hazards even when their vision misleads them to think that the ground is clear and flat.
The final stage of learning to use a cane is proficiency when distracted and noticing and using information provided by a cane even if it is not consistent with visual information or expectations about the area. There seem to be three issues that can affect a student's achievement of the final stage of learning. They are the level of attention required to notice information provided by a cane, the ability to use the proprioceptive information from the cane, and the ability to override misleading visual information with reliable cane or nonvisual information.
Discussion and conclusions
- Level of attention required to notice information provided by a cane
Students should be able to move the cane correctly without concentrating on it, but they should also be attentive enough to be able to notice whenever the cane seems to deviate from being on ground level. The only intervention that we have found necessary for students to overcome insufficient attention is repeated practice in approaching and detecting unexpected drop-offs (with appropriate monitoring for safety). When opportunities are presented, instructors may point out how important it is to notice the cane information by pointing out any severe, unbarricaded drop-offs or holes that they pass.
- Ability to use proprioceptive information from the cane
Students need to understand what the cane feels like when the tip is on the same level as they are and what it feels like when the tip is slightly dropped or raised. This understanding requires good proprioception.
A change in the level of a surface is translated into a slight change in the angle of the cane, which is much more noticeable in the wrist than in the elbow or shoulder. According to Rosen (personal communication, December 15, 2008), moving the wrist "sets off proprioceptive signals that are more readily noticed than when a joint moves within its range. Because there is so much more of a normal range of motion at the elbow, the tendons do not get stretched to their limit, and there is less proprioceptive input."
Thus, a change in the level of a surface will be more noticeable if a student is moving the cane only with wrist movement and not by moving his or her arm. To help students notice how a change in the level of the cane tip changes the angle of the wrist, have them stand with the side of their feet next to the edge of a curb and hold the cane out ahead in the normal position, such that the tip is at the top edge of the curb. Ask the students to move the cane slightly, so it goes over the edge, and have them notice the change. If they are holding the arm still and moving only the wrist when the tip goes over the edge, there is a stretch along the top of the wrist. If they do not notice that stretch, do it again at a deeper drop-off, such as a stair, so they notice the change and then do it again at a curb. Once students notice that stretch in their wrist, they can improve with repetition; have them continue to stand beside the curb and repeat moving the cane up and down to the top and bottom of the curb until they are satisfied that they can notice the wrist stretch readily. Once they have accomplished this task, have them approach curbs and notice the drop.
If students are still having difficulty noticing the change in the angle of the cane dropping over an edge, make sure that the cane is no longer than is necessary to provide adequate coverage. The difference in the angles of shorter canes dropping over an edge is larger than it is for longer canes, making it easier to feel shorter canes drop over an edge. Rodgers and Emerson (2005) found that the length of a cane is a significant factor in detecting drop-offs: "If the cane is too long, a clear indication of a drop-off may not be afforded" (p. 629). We also note that there are consequences of a cane that is too short because the cane may not give sufficient warning for the student to react to the drop-off (Rogers & Emerson, 2005). Instructors should be cognizant of both situations.
We have observed that the proprioception of some students, such as those with diabetic neuropathy, may be insufficient to notice the change in the angle of the cane no matter how much practice they get. For such students, the constant-contact cane technique may be more effective for noticing drop-offs because the change in the angle may be more abrupt or salient and accompanied by a change in the sound of the tip along the ground.
Do not assume, however, that whenever there is a loss of skin sensation, there is an equal loss of proprioception, because the receptors for proprioception are in the muscles and neurotendinous organs (Santos, Bertato, Montebelo, & Guirro, 2008, p. 185), not the skin. We have found that many clients who have a reduced sense of touch are nevertheless able to feel subtle changes in the angle of their wrist.
- Ability to override misleading visual information
Students who have had a lifetime of using vision do not readily switch to relying on other sensory information while traveling. Although some individuals can make this switch without special intervention, many cannot. When they see what looks like flat ground and the cane drops over an edge, they often believe their eyes and do not even notice the cane information.
To override visual information with reliable cane or nonvisual information, we suggest a strategy--partial occlusion--that can help teach students who have functional vision to notice tactile (nonvisual) information provided by a cane. Partial occlusion blocks only the lower, bottom part of their vision; thus, students are still able to see ahead of them and look around but are unable to see anything on the ground directly in front of them, such that the only way they can know what is on the ground is by the information their cane provides them. This strategy gives them the experience of being distracted by their usable vision while having to rely on nonvisual information from the cane for their safety while traveling.
Partial occlusion should be introduced only after the students have reached the third level of cane proficiency, not only because the instructor should avoid distracting first- and second-level students with other tasks while they concentrate on learning to use the cane, but because the purpose of using partial occlusion is to help students develop trust and awareness of the cane information. If a student has not yet achieved the proficiency required to provide reliable cane protection, partial occlusion may lead to a distrust of the cane that will be difficult to overcome. For the same reason, before students are trained with partial occlusion they should be made aware of the three things that the cane may not detect (see Box 1), so they are not disillusioned and do not become distrustful of the information provided by the cane.
Partial occlusion has a secondary benefit for students who tend to focus all their attention on scanning the ground visually to detect obstacles and edges. Students who often walk with an anterior head tilt, which compromises their balance and causes them to be oblivious to what is around them, benefit from partial occlusion because it may help them realize how dependent they are on looking down. If these students have developed a reliable cane technique, they may learn during partial occlusion that it is not necessary to look down to navigate obstacles and steps.
Vision can be partially occluded with eyeglasses, sunglasses, or goggles that have the bottom half of the lenses or lens openings covered with material like paper, cardboard, or plastic (see Figure 1). The placement of the occlusion material will depend on the individual. It should allow students to see straight ahead but not see the ground in front of their feet. After positioning the occlusion, ask the students to hold their heads upright and report what is visible and then reposition the material to occlude the desired amount. Commonly, the area that is occluded is the ground about 10-15 feet in front of the student, but an instructor may want to occlude more or less, depending on the situation and goal (see Figures 2 and 3).
Exercises that can be done while a student is wearing eyewear with partial occlusion include the following:
1. The student walks through various familiar and unfamiliar routes, including stairs or curbs, becoming accustomed to relying on the cane for surface information.
2. The student walks through an obstacle course or walks where there are curbs and steps.
3. The student practices noticing the nonvisual information while being distracted with another task, such as listening for a certain sound or looking for a certain door.
- Negotiating obstacles
In addition to being proficient in the fourth stage of learning to use a cane, students need and deserve instruction that enables them to notice and negotiate hazards reliably. Anything less leaves them unprepared to travel safely but under the impression that using the cane will make them safe.
When students try to walk around an obstacle, common mistakes include sidestepping to get around the obstacle, anchoring the cane tip at the obstacle while they walk around it, or starting to walk around the obstacle but turning to resume their original path of travel too soon so that they trip or catch their foot on the obstacle. Sidestepping into a space that has not been checked by the cane or anchoring the cane on the obstacle while walking around it leaves students vulnerable to tripping or falling over obstacles or drop-offs that they had not been aware were there. Turning too soon when they think they have passed the edge or corner of the obstacle can cause students to trip or stumble on the obstacles. Students need to learn that when they encounter an obstacle, they should use their cane to look for a clearing or opening beside the obstacle and then turn to walk into that opening (rather than sidestep it), continue to move the cane in an arc ahead of them while passing the obstacle, and return to the line of travel only after they have passed the obstacle.
All these tasks are intuitive and easy to learn except the last. Many students do not realize that when the cane tip reaches the end of the obstacle, they themselves have not yet reached the end of the obstacle, and they turn to walk around the obstacle or resume their line of travel too soon, tripping or catching their foot on the obstacle that they were trying to pass. It takes practice to realize how much farther they have to walk after the cane passes the obstacle before they themselves pass it. The following are some exercises that can help:
1. The students walk along a wall toward an outside corner, sliding the cane tip along the edge or shorelining the wall. When the tip of the cane goes around the corner, they walk forward and notice how long it takes to get around the corner (students can feel the wall with their hand or use echolocation to notice when the end is reached).
2. Once the students understand how much distance there is between them and the cane's tip, they should do the same exercise, but instead of using a wall, they should trail or shoreline with the cane along a carpet or sidewalk approaching a corner of the carpet or sidewalk. When the cane reaches the corner, they should keep walking and moving the cane normally to check ahead for more hazards, but remember where the corner is. Ask the students to turn around the corner of the carpet or sidewalk when they think they are past it. They will know they have turned too soon if they step on carpet or grass instead of the floor or sidewalk.
3. Once the students have mastered the previous exercise, they should do the same thing along a low wall or border, such as a planter, turning the corner when they think they are past it. They will know they have not walked far enough before turning if their foot touches the planter.
- Negotiating stairs with impaired vision
Much has been written about techniques for negotiating stairs (Hill & Ponder, 1976; Jacobson, 1993), but we address the issue of students who negotiate stairs while straining to use their vision, rather than using more reliable cane information. Students often lean forward to see better, which can jeopardize their balance.
Intermittent occlusion can be effective to help students rely on information provided by the cane. With intermittent occlusion, students perform tasks visually and then repeat them with visual occlusion (using a blindfold or with their eyes closed), so they can more easily notice the nonvisual information, and then repeat the task again without occlusion while using the nonvisual information that they had noticed previously.
For example, many students who have learned to approach and go down stairs with a blindfold will lean forward the first time they approach a curb or descending stairway without the blindfold and strain to see the edge. The instructor may let them find the edge and then ask them to approach the curb again with their eyes closed. Typically, students perform this task well and find the edge with confidence, as they did earlier with a blindfold. Then they approach the edge with their eyes open, using the cane as they did before. Most students need to repeat this experience; after enough of these experiences of intermittent occlusion, they start to notice and use their canes to detect curbs with confidence and without further prompting.
Instructors can enhance the effectiveness of learning to use a long cane. By using practices that ensure that students advance successfully through the stages of acquiring skills, including addressing the tasks of negotiating obstacles and stairs, O&M specialists ensure that the cane delivers the information needed for safe travel and that travelers can interpret and use the input from their canes. Being aware of current hypotheses related to memory and motor tasks, instructors can improve the long-term performance of cane travelers.
Strategies for providing instruction in the use of the cane are effective only for those who are motivated to learn to notice and use nonvisual information for everyday situations, including situations in which their vision is compromised because of lighting conditions. These strategies are not as likely to help those who are not motivated, such as those whose vision provides sufficient information in all conditions or who are in training only to prepare for future vision loss.
Ackerman, P. L. (2007). New developments in understanding skilled performance. Current Directions in Psychological Science, 16, 235-239.
Adi-Japha, E., Karni, A., Parnes, A., Loewenschuss, I., & Vakil, E. (2008). A shift in task routines during the learning of a motor skill: Group-averaged data may mask critical phases in the individuals' acquisition of skilled performance. Journal of Experimental Psychology: Learning, Memory, and Cognition, 34, 1544-1551.
Diekelmann, S., & Born, J. (2007). One memory, two ways to consolidate? Nature Neuroscience, 10, 1085-1086.
Hill, E., & Ponder, P. (1976). Orientation and mobility techniques: A guide for the practitioner. New York: American Foundation for the Blind.
Jacobson, W. H. (1993). The art and science of teaching orientation and mobility to persons with visual impairments. New York: American Foundation for the Blind.
Jacobson, W. H., & Bradley, R. H. (1997). Learning theory and teaching methodologies. In B. B. Blasch, W. R. Wiener, & R. L. Welsh (Eds.), Foundations of orientation and mobility (2nd ed., pp. 359-382). New York: AFB Press.
Maas, E., Robin, D. A., Austermann Hula, S. N., Freedman, S. E., Wulf, G., Ballard, K. J., & Schmidt, R. A. (2008). Principles of motor learning in treatment of motor speech disorders. American Journal of Speech-Language Pathology, 17, 277-298.
Martinsen, H., Tellevik, J. M., Elmerskog, B., & Storlilokken, M. (2007). Mental effort in mobility route learning. Journal of Visual Impairment & Blindness, 101, 327-338.
Rodgers, M. D., & Emerson, R. W. (2005). Human factor analysis of long cane design: Weight and length. Journal of Visual Impairment & Blindness, 99, 622-632.
Santos, A. A., Bertato, F. T., Montebelo, M. I. L., & Guirro, E. C. O. (2008). Effect of proprioceptive training among diabetic women. Revista Brasileira de Fisioterapia, 12(3), 183-187.
Schilling, M. A., Marangoni, A., Vidal, P., & Rajan, M. (2000, August). Learning by doing something else: The impact of task variation on organizational learning curves. Paper presented at the annual meeting of the Academy of Management, Toronto, Ontario, Canada.
Sullivan, K. J., Kantak, S. S., & Burtner, P. A. (2008). Motor learning in children: Feedback effects on skill acquisition. Physical Therapy, 88, 720-732.
Walker, M. P., Brakefield, T., Hobson, J. A., & Stickgold, R. (2003). Dissociable stages of human memory consolidation and reconsolidation. Nature, 425(6958), 616-620.
Whitehead, A. N. (1911). An introduction to mathematics. New York: Henry Holt.
Dona Sauerburger, M.A., COMS, orientation and mobility specialist, 1606 Huntcliff Way, Gambrills, MD 21054; e-mail: <firstname.lastname@example.org>.
Eugene Bourquin, DHA, CLVT, COMS, senior instructor, Helen Keller National Center for Deaf-Blind Youths and Adults; mailing address: 315 8th Avenue, 10E, New York, NY 10001; e-mail: <email@example.com>.
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