00331nam a22001337a 4500 PB. FIZZA ISHAQ 004.6 GIL HELD, GILBERT. 36816 UNDERSTANDING DATA COMMUNICATIONS / GILBERT HELD OTTAWA : JOHN WILLEY, 1991. 546 P. ; ddc BK 566361 566361 0 0 ddc 0 0 NQC NQC 2021-06-25 0 004.6 GIL Q-2009 2021-06-25 2021-06-25 BK