000 00286nam a2200121Ia 4500
008 220201s1981 xx 000 0 eng d
082 _a621.386
_bDAS
100 _aDas, P N
245 0 _aIntroduction to automatic telephoney
260 _aCalcutta
_c1981
300 _a244
942 _2ddc
999 _c24578
_d24578