TY  - BOOK
AU  - Perkins, W.T.
TI  - Modern telegraph systems and eqipment covering voice frequency,telex,sub-audio and varioplex systems,and all types of modern apparatus including the teleprinter,teletypewriter and creed automatic 5-unit and morse equipment with 126 illus
U1  - 621.382 
PY  - 1946///
CY  - London
PB  - George
ER  -