Tolba, M. K., Lamb, R., & Allen, P. (1983). Earth matters: Environmental challenges for the l980s. United Nations Environment Programme.
Chicago-viite (17. p.)Tolba, Mostafa Kamal, Robert Lamb, ja Patrick Allen. Earth Matters: Environmental Challenges for the L980s. Nairobi, Kenya: United Nations Environment Programme, 1983.
MLA-viite (9. p.)Tolba, Mostafa Kamal, et al. Earth Matters: Environmental Challenges for the L980s. United Nations Environment Programme, 1983.
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