00286nam a2200109 a 4500008004100000050001600041100002100057245003700078260003600115300001600151350000900167120416s1974    ||||||||||||||||| ||    u  aTK 5101 Ove  aOverman, Michael10aUnderstanding Telecommunications  aLondonbLutterworth Pressc1974  a192p. : ill  a0.00