APA (7th ed.) Zitazioa

Wallen, R. N. (1992). Introduction to physical geography. WM C. Brown.

Chicago Style (17th ed.) Zitazioa

Wallen, Robert N. Introduction to Physical Geography. Boulevard: WM C. Brown, 1992.

MLA (9th ed.) Zitazioa

Wallen, Robert N. Introduction to Physical Geography. WM C. Brown, 1992.