Pursell, C. W. (1973). From conservation to ecology: The development of environmental concern. Crowell.
Chicago-referens (17:e uppl.)Pursell, Carroll W. From Conservation to Ecology: The Development of Environmental Concern. New York: Crowell, 1973.
MLA-referens (9:e uppl.)Pursell, Carroll W. From Conservation to Ecology: The Development of Environmental Concern. Crowell, 1973.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.