APA (7th ed.) Zitazioa

Open University. (1974). Grupos. McGraw-Hill Latinoamericana.

Chicago Style (17th ed.) Zitazioa

Open University. Grupos. Colón: McGraw-Hill Latinoamericana, 1974.

MLA (9th ed.) Zitazioa

Open University. Grupos. McGraw-Hill Latinoamericana, 1974.