TY  - BOOK
AU  - Kessler, Gary C.
TI  - ISDN Concepts Facilities and Services 
SN  - 0070342423
U1  - 621.382 
PY  - 1990///
CY  - New York : 
PB  - McGraw-Hill, 
KW  - Integrated Services Digital Networks
N1  - YY
UR  - https://eaklibrary.neduet.edu.pk:8443/catalog/bk/books/toc/0-07-034242-3.pdf
ER  -