00525nam a2200205Ia 4500 127 BD-ChIIU 150105s9999 xx 000 0 und d Nil 384.6/B621p Biswas, N. N. Principles Of Telephony 1st New Delhi UBS Publishers Distributors Ltd 1998 138 Yes 21cm Telephone, Principle Department of Computer Science & Engineering Telephone ddc BK 2121 2121