APA (7th ed.) Citation

(1971). The key to English: Two-word verbs. Collier-Macmillan.

Chicago Style (17th ed.) Citation

The Key to English: Two-word Verbs. London: Collier-Macmillan, 1971.

MLA (9th ed.) Citation

The Key to English: Two-word Verbs. Collier-Macmillan, 1971.

Warning: These citations may not always be 100% accurate.