00274nam a2200109Ia 4500008004100000041000800041082001700049100001500066245002800081260004500109300001000154220530s9999    xx            000 0 und d  aeng  a623.733bBIS  aBiswas N N  aPrinciples of Telephony  aNew DelhibUBS Publlishers Pvt Ltdc2004  a138 P