000 00308nam a2200121Ia 4500
008 250409s9999 xx 000 0 und d
020 _a81-203-2555-9
082 _a4.6
_bHEL
100 _aHeld, Gilbert
245 0 _aUnderstanding data communications 4/E
260 _aVidhyanagar
_bPHI
_c2007
365 _a250
999 _c254969
_d254969