Cunningham, W. P., & Cunningham, M. A. Principles of Environmental Science (9th ed.). Unknown.
Chicago Style (17. basım) AtıfCunningham, William P., ve Mary Ann Cunningham. Principles of Environmental Science. 9th ed. Unknown: Unknown.
MLA (9th ed.) AtıfCunningham, William P., ve Mary Ann Cunningham. Principles of Environmental Science. 9th ed. Unknown.
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