APA (7th ed.) Citation

Milne, L., Milne, M. J. G., & Shortt, T. M. (1956). The world of night. Harper.

Chicago Style (17th ed.) Citation

Milne, Lorus, Margery Joan Greene Milne, and T. M. Shortt. The World of Night. New York: Harper, 1956.

MLA (8th ed.) Citation

Milne, Lorus, et al. The World of Night. Harper, 1956.