Dyfyniad APA
Koch, P. (2010). Water sources (4th ed.). American Water Works Association.
Dyfyniad Arddull Chicago
Koch, Paul. Water Sources. 4th ed. Denver, Colo.: American Water Works Association, 2010.
Dyfyniad MLA
Koch, Paul. Water Sources. 4th ed. American Water Works Association, 2010.
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