Kircher, H. B., Wallace, D. L., & Gore, D. J. (1988). Our natural resources and their conservation (6th ed.). Interstate Printers & Publishers.
Chicago-referens (17:e uppl.)Kircher, Harry B., Donald L. Wallace, och Dorothy J. Gore. Our Natural Resources and Their Conservation. 6th ed. Danville, Ill.: Interstate Printers & Publishers, 1988.
MLA-referens (9:e uppl.)Kircher, Harry B., et al. Our Natural Resources and Their Conservation. 6th ed. Interstate Printers & Publishers, 1988.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.