APA (7th ed.) Zitazioa
ebrary, Inc, & Sack, R. D. (2002). Progress: Geographical essays. Johns Hopkins University Press.
Chicago Style (17th ed.) Zitazioa
ebrary, Inc, eta Robert David Sack. Progress: Geographical Essays. Baltimore: Johns Hopkins University Press, 2002.
MLA (9th ed.) Zitazioa
ebrary, Inc, eta Robert David Sack. Progress: Geographical Essays. Johns Hopkins University Press, 2002.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.