Pursell, C. W. (1973). From conservation to ecology: The development of environmental concern. Crowell.
Lua i Stíl Chicago (17ú heag.)Pursell, Carroll W. From Conservation to Ecology: The Development of Environmental Concern. New York: Crowell, 1973.
Lua MLA (9ú heag.)Pursell, Carroll W. From Conservation to Ecology: The Development of Environmental Concern. Crowell, 1973.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.