Gaya APA
LUTGENS, F, K.
(2006).
ESSENTIALS OF GEOLOGY
(
NINTH EDITION)
.
United State of America:
Prentice Hall.
Gaya MLA
LUTGENS, FREDERICK, K..
"ESSENTIALS OF GEOLOGY".
NINTH EDITION
United State of America:
Prentice Hall,
2006.
Textbook.