Perman, R. (2011). Natural resource and environmental economics (4th ed.). Pearson Education.
Lua i Stíl Chicago (17ú heag.)Perman, Roger. Natural Resource and Environmental Economics. 4th ed. Harlow, Essex, Eng: Pearson Education, 2011.
Lua MLA (9ú heag.)Perman, Roger. Natural Resource and Environmental Economics. 4th ed. Pearson Education, 2011.
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