Cita APA (7th ed.)

Raven, P. H., & Johnson, G. B. (1991). Understanding biology (2nd ed.). Wm. C. Brown Publishers.

Cita Chicago (17th ed.)

Raven, Peter H., i George B. Johnson. Understanding Biology. 2nd ed. Dubuque, IA: Wm. C. Brown Publishers, 1991.

Cita MLA (9th ed.)

Raven, Peter H., i George B. Johnson. Understanding Biology. 2nd ed. Wm. C. Brown Publishers, 1991.