Cita APA (7th ed.)

Carwardine, M. (1990). The WWF environment handbook. MacDonald Optima.

Cita Chicago (17th ed.)

Carwardine, Mark. The WWF Environment Handbook. London: MacDonald Optima, 1990.

Cita MLA (9th ed.)

Carwardine, Mark. The WWF Environment Handbook. MacDonald Optima, 1990.