TY  - BOOK
AU  - Boltianskii, V. G.
TI  - Envelopes
SN  - 2028
U1  - 516 
PY  - 1964///
CY  - New York
PB  - Pergamon Press
KW  - Envelopes (Geometry)
N1  - "A Pergamon Press book."
ER  -