TY  - BOOK
AU  - Held 
TI  - Understanding data communications 
SN  - 0672305011 
U1  - 001.64404 HEL 1994 
PY  - 1994///
CY  - Indianapolis
PB  - Sams
KW  - Computer networks
KW  - Data transmission systems
N1  - Includes bibliographical references (p. [403]-404) and index; Previous eds. written by George E. Friend ... et al
ER  -