EPA Journal. US Environmental Protection Agency.
Chicago Style (17. basım) AtıfEPA Journal. US Environmental Protection Agency.
MLA (9th ed.) AtıfEPA Journal. US Environmental Protection Agency.
Uyarı: Bu alıntı herzaman %100 doğru olmayabilir..
EPA Journal. US Environmental Protection Agency.
Chicago Style (17. basım) AtıfEPA Journal. US Environmental Protection Agency.
MLA (9th ed.) AtıfEPA Journal. US Environmental Protection Agency.