TY  - BOOK
AU  - Gerlach, Vernon S 
AU  - Ely , Donald P
TI  - Teaching and Media : a systematic approach 
SN  - 0138913587
U1  - 371.3 
PY  - 1980///
CY  - New Jersey
PB  - prentice hall 
KW  - Audio-visual  education
KW  - Teaching
ER  -