TY  - BOOK
AU  - Helmers,Scott A.
TI  - Data communications: a beginner's guide to concepts and technology
SN  - 0131988700
PY  - 1989///
CY  - Englewood Cliffs, N.J.
PB  - Prentice-Hall
KW  - Data transmission systems
KW  - Computer network
N1  - Includes bibliographical references and index
ER  -