000 00256nam a2200109Ia 4500
008 190516s9999 xx 000 0 und d
100 _aHELD(GILBERT)
245 0 _aUNDERSTANDING DATACOMMUNICATIONS
260 _c2007
_bPEARSON
300 _a765
942 _cBK
999 _c16861
_d16861