000			00345nam a2200157Ia 4500
008			190201s9999 xx 000 0 und d
020			_a9.78E+12
082			_a4
082			_b6 HEL
100			_a"Held, Gilbert"
245		0	_aUnderstanding Data Commu
260			_aNew York
260			_bJohn Wiley &Sons
260			_c1997
300			_a728
999			_c36730 _d36730