TY  - BOOK
AU  - Helgert, Hermann J.,
TI  - Integrated services digital networks: Architectures, protocols, standards 
SN  - 0-201-52501-1
AV  - TK5103.7 H45
PY  - 1991///
CY  - Reading, massachusetts
PB  - Addison-wesley
KW  - Redes digitales de servicios integrados
ER  -