William P. Cunningham, M. A. C. Environmental science a global concern. McGraw-Hill.
Lua i Stíl Chicago (17ú heag.)William P. Cunningham, Mary Ann Cunningham. Environmental Science a Global Concern. McGraw-Hill.
Lua MLA (8ú heag.)William P. Cunningham, Mary Ann Cunningham. Environmental Science a Global Concern. McGraw-Hill.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.