Cita APA (7a ed.)

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

Cita Chicago Style (17a ed.)

Knapp, Brian J., Duncan McCrae, y S.R.J Ross. Challenge of the Natural Environment. Essex: Longman, 1989.

Cita MLA (9a ed.)

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