Gaya APA
Gregory, K, J., Walling, D, E. (1973).
Drainage Basin Form and Process : Geomorphological Approach .
New York:
Halsted.
Gaya MLA
Gregory, K, J., Walling, D, E.
"Drainage Basin Form and Process : Geomorphological Approach".
New York:
Halsted,
1973.
Text.