TY  - BOOK
AU  - Open University T321
TI  - Telecommunication systems course : units 7-9. Telephone systems : study supplement
SN  - 0335061036
U1  - TK/5101 
PY  - 1976///
CY  - Milton Keynes
PB  - Open University Press
KW  - Telecommunication systems.
ER  -