TY  - BOOK
AU  - Z T Bieniawski
TI  - Engineering Rock Mass Classification : A Complete Mannual For Engineers And Geologists in Mining ,Civil and Petroleum Engineering
SN  - 9780471601722
U1  - 624.15132 
PY  - 1989///
CY  - Canada, New York
PB  - Wiley -Interscience publications, John Wiley And Sons
ER  -