00488nam a2200169 a 4500008004100000020001500041020001500056050001600071100002000087245009500107250001100202260004500213300002300258350000900281650001400290650001400304060316s1978    ||||||||||||||||| ||    u  a0198593589  a0198593570  aTK 6161 Smi  aSmith, Sydney F10aTelephony and telegraphy : an introduction to instruments and switching systems. (3rd ed.)  a3d ed.  aOxford :bOxford University Pressc1978.  axiv, 278 p. : ill.  a0.00  aTELEGRAPH  aTELEPHONE