APA (7th ed.) Zitazioa

Spencer, D. (1963). English for proficiency. Oxford University Pr.

Chicago Style (17th ed.) Zitazioa

Spencer, D.H. English for Proficiency. London: Oxford University Pr, 1963.

MLA (9th ed.) Zitazioa

Spencer, D.H. English for Proficiency. Oxford University Pr, 1963.