APA (7th ed.) Zitazioa

Scheffer, J. (1975). The Progressive in English. North-Holland.

Chicago Style (17th ed.) Zitazioa

Scheffer, Johannes. The Progressive in English. Amsterdam: North-Holland, 1975.

MLA (9th ed.) Zitazioa

Scheffer, Johannes. The Progressive in English. North-Holland, 1975.