TY  - BOOK
AU  - McKown,Harry C.
AU  - Roberts,Alvin
TI  - Audio-visual aids to instruction
T2  - McGraw-Hill series in education, Harold Benjamin, consulting editor
U1  - 371.33 
PY  - 1949///
CY  - New York and, London
PB  - McGraw-Hill book company, inc
KW  - Audio-visual education
N1  - "Selected references" at end of each chapter except chapter III. "Sources of materials and equipment": p.579-595
ER  -