Allen, J. L. (2004). Environment 04/05 (Twenty-third edition.). Mcgraw-Hill/Dushkin.
Lua i Stíl Chicago (17ú heag.)Allen, J. L. Environment 04/05. Twenty-third edition. Dubuque, Iowa: Mcgraw-Hill/Dushkin, 2004.
Lua MLA (9ú heag.)Allen, J. L. Environment 04/05. Twenty-third edition. Mcgraw-Hill/Dushkin, 2004.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.