APA (7th ed.) Citation

Crook, H. C. (1951). Campanulas: Their cultivation and classification. New York.

Chicago Style (17th ed.) Citation

Crook, H. Clifford. Campanulas: Their Cultivation and Classification. London, Country Life : Scribner: New York, 1951.

MLA (9th ed.) Citation

Crook, H. Clifford. Campanulas: Their Cultivation and Classification. New York, 1951.