(Earth Works Group (U.S. (1989). 50 simple things you can do to save the earth. Earthworks Press.
Chicago-referens (17:e uppl.)(Earth Works Group (U.S. 50 Simple Things You Can Do to Save the Earth. .Berkeley, CA: Earthworks Press, 1989.
MLA-referens (9:e uppl.)(Earth Works Group (U.S. 50 Simple Things You Can Do to Save the Earth. Earthworks Press, 1989.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.