APA (7th ed.) Citation

Calkins, G. N., & Summers, F. M. (1941). Protozoa in biological research. Columbia university press.

Chicago Style (17th ed.) Citation

Calkins, Gary N., and Francis M. Summers. Protozoa in Biological Research. New York: Columbia university press, 1941.

MLA (9th ed.) Citation

Calkins, Gary N., and Francis M. Summers. Protozoa in Biological Research. Columbia university press, 1941.