00333nam a2200133Ia 4500008004100000041000800041082001900049100001400068245005000082250001200132260003300144300000800177700001400185240509s9999    xx            000 0 und d  aeng  a004.6 SHAbSHA  aShay W.A.  aUnderstanding Data Communication and Networks  a2nd ed.  bBrooks/Cole Publishing Comp.  a711  aShay W.A.