TY  - BOOK
AU  - Levens, A. S.
AU  - Schneider,  F. H. ,
AU  - Walter,  L. C.,
TI  - Graphics in Engineering Design: workbook 1, a general treatment of engineering graphics 
SN  - 047103133X
U1  - 604.2 23
PY  - 1980///
CY  - New York
PB  - John wiley, 
ER  -