Gaya APA
Clifford, T. (2011).
Rourke's world of science encyclopedia Vol. 7 : astronomy and space .
Florida:
Rourke Publshing.
Gaya MLA
Clifford, Tim.
"Rourke's world of science encyclopedia Vol. 7 : astronomy and space".
Florida:
Rourke Publshing,
2011.
Text.