TY  - GEN
AU  - Schuller, Charles Francis
AU  - Wittich, Walter Arno
TI  - Audio visual meterials : their nature and use
T2  - Exploration series in education
U1  - 371.33 WIT 
CY  - New York, Harper & Row publishers
KW  - Education/ teaching methods/ audio - visual materials/ programmed learning
ER  -