Cita APA (7th ed.)

Knapp, B., McCrae, D., & Ross, S. (1989). Challenge of the natural environment. Longman.

Cita Chicago (17th ed.)

Knapp, B.J, D.L.R McCrae, i S.R.J Ross. Challenge of the Natural Environment. Essex, Eng: Longman, 1989.

Cita MLA (9th ed.)

Knapp, B.J, et al. Challenge of the Natural Environment. Longman, 1989.