TY  - GEN
AU  - Held, Gilbert,               
TI  - Understanding data communications
SN  - 8176353191
U1  - 004.6 
PY  - 2002///
CY  - Boston
PB  - Addison
KW  - Data transmission systems
KW  - Computer networks
N1  - Previous eds. written by George E. Friend ... et al
ER  -