Gaya APA

, ., Penck, W. (1972). Morphological analysis of land forms a contribution to phsical geology . New York: New York: Hafner; 1972.

Gaya MLA

, ., Penck, Walther. "Morphological analysis of land forms a contribution to phsical geology". New York: New York: Hafner; 1972, 1972. Text.