Tohutoro APA (7th ed.)

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

Tohutoru Kātū Chicago (17th ed.)

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

Tohutoro MLA (9th ed.)

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