Cita APA (7th ed.)

English Language Services. (1968). A practical english grammar. Collier Macmillan International.

Cita Chicago (17th ed.)

English Language Services. A Practical English Grammar. Nueva York: Collier Macmillan International, 1968.

Cita MLA (9th ed.)

English Language Services. A Practical English Grammar. Collier Macmillan International, 1968.