WitcherC. M., “General Considerations on Guidance Devices” (March, 1949), distributed by Prosthetic and Sensory Aid Service, Veterans AdministrationNew York, N. Y.
2.
WitcherC. M., “Some Communication Aspects of Visual Prosthesis” (December, 1953), not yet published, but available from this laboratory.
3.
BenhamT. A., “Evaluation and Development of a Guidance Device for the Blind” (December, 1953), available from Professor T. A. Benham, Haverford CollegeHaver-ford, Pennsylvania.
