Citing an encyclopedia entry in print
F.M. (Publication year). Entry title. In Encyclopedia title. (Vol. XX, pp. XX-XX). City, State of publication: Publisher.
Note: Tertiary sources are not typically appropriate for research papers. Check with your instructor.
McGhee, K., & McKay, G. (2007). Insects. In Encyclopedia of animals (p.175). Washington, D.c.: National Geographic Society.