TY  - BOOK
AU  - Held, Gilbert.
TI  - Understanding data communications
SN  - 8129702118
U1  - 004.65  7
PY  - 2003///
CY  - New Delhi
PB  - Pearson Education
KW  - Messages and transmission channels
KW  - Asynchronous modems and interfaces
KW  - Synchronous modems digital transmission and service units
ER  -