Cita APA (7a ed.)

English Language Services. (1964). The key to english. Collier-Macmillan.

Cita Chicago Style (17a ed.)

English Language Services. The Key to English. London: Collier-Macmillan, 1964.

Cita MLA (8a ed.)

English Language Services. The Key to English. Collier-Macmillan, 1964.