TY  - BOOK
AU  - Williams. Howel
TI  - Petrography: An introd. to the study of rocks in thin sections 
T2  - A series of geology texts
AV  - QE431 W53
PY  - 1954///
CY  - San francisco
PB  - W. H. Freeman
KW  - Petrología
ER  -