APA (7th ed.) Citation

Tolba, M. K., Lamb, R., & Allen, P. (1983). Earth matters. UNEP.

Chicago Style (17th ed.) Citation

Tolba, Mostafa Kamal, Robert Lamb, and Patrick Allen. Earth Matters. Nairobi, Kenya: UNEP, 1983.

MLA (9th ed.) Citation

Tolba, Mostafa Kamal, et al. Earth Matters. UNEP, 1983.