TY  - BOOK
AU  - Held,Gilbert
TI  - Understanding data communications: from fundamentals to networking 
SN  - 0471627453
AV  - TK5105  .H444 2000
PY  - 2000///
CY  - Chichester
PB  - John Wiley
KW  - Data transmission systems
KW  - Computer networks
ER  -