TY - BOOK AU - Boltianskii, V. G. AU - Brown, Robert B. TI - ENVELOPES U1 - 516.7 PY - 1964/// CY - N. Y. PB - Macmillan KW - Envelopes (Geometry) N1 - Translation Of Ogibaniushchaia; A Pergamon Press Book; Popular Lectures In Mathematics, V. 12 ER -