00357nam a2200133Ia 4500008004100000040001700041041001200058082001700070100001800087245006000105250001200165260003500177300001100212230917s9999||||xx |||||||||||||| ||und||  e192928aMAIN  aEnglish  a004.64 H165D  aHalsall, Fred 0aData communications, computer networks and open systems  a4th ed.  aDelhibPearson Educationc2005  a915 p.