Freedman, B. (2001). Environmental science: A Canadian perspective. Prentice Hall.
Lua i Stíl Chicago (17ú heag.)Freedman, Bill. Environmental Science: A Canadian Perspective. Toronto: Prentice Hall, 2001.
Lua MLA (8ú heag.)Freedman, Bill. Environmental Science: A Canadian Perspective. Prentice Hall, 2001.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.