Christopherson, R. W. (2006). Geosystems (Custom edition for Georgia State University.). Pearson Custom Publishing.
Chicago-viite (17. p.)Christopherson, Robert W. Geosystems. Custom edition for Georgia State University. Boston, Ma: Pearson Custom Publishing, 2006.
MLA-viite (9. p.)Christopherson, Robert W. Geosystems. Custom edition for Georgia State University. Pearson Custom Publishing, 2006.
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