00755nam a2200241Ia 4500 HEL-DAT-ONS-9780131988705 20260729073151.0 260729s9999 xx 000 0 und d 9780131988705 PK-LaCU English 621.3981 HEL HEL Helmers,Scotta Data communications A beginner's guide to concepts and technology New Jersey Prentice Hall 1989 xviii 558 Soft Binding 390 Rs. Faculty, students and Staff Electrical Engineering Data, communications DDC BK HEL 12516 12516