APA (7th ed.) Citation

Galtrey, S., Edwards, L., & Haig, D. (1918). The horse and the war. "Country life" [etc.].

Chicago Style (17th ed.) Citation

Galtrey, Sidney, Lionel Edwards, and Douglas Haig. The Horse and the War. London: "Country life" [etc.], 1918.

MLA (9th ed.) Citation

Galtrey, Sidney, et al. The Horse and the War. "Country life" [etc.], 1918.