TY  - BOOK
AU  - Held, Gilbert
TI  - Understanding data communications
SN  - 672322161
SN  - 200108958
U1  - 004.6 HEL 
PY  - 2002///
CY  - Boston, MA
PB  - Addison-Wesley
KW  - Computer networks
KW  - Data transmission systems
N1  - Includes bibliographical references and index
ER  -