APA (7th ed.) Zitazioa
Gravil, R. (2007). Existentialism. Humanities-Ebooks.
Chicago Style (17th ed.) Zitazioa
Gravil, Richard. Existentialism. Tirril [England]: Humanities-Ebooks, 2007.
MLA (9th ed.) Zitazioa
Gravil, Richard. Existentialism. Humanities-Ebooks, 2007.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.