TY  - BOOK
TI  - Illustrated science and invention encyclopedia : how it works vol. 20
U1  - 603.21 
PY  - 1976///
CY  - New York
PB  - H.S.Stuttman
KW  - Encyclopedia
KW  - Science
KW  - Technology
N1  - Welding zworykin historic events
ER  -