Gaya APA
Clifford, T.
(2011).
Rourke's world of science encyclopedia Vol. 4 Earth Science
.
Florida:
Rourke Publshing.
Gaya MLA
Clifford, Tim.
"Rourke's world of science encyclopedia Vol. 4 Earth Science".
Florida:
Rourke Publshing,
2011.
Text.