Willman, H. B., & Frye, J. C. (1980). The glacial boundary in southern Illinois. Illinois Institute of Natural Resources, Illinois State Geological Survey Division.
Chicago Style (17th ed.) CitationWillman, H. B., and John C. Frye. The Glacial Boundary in Southern Illinois. Urbana, Ill.: Illinois Institute of Natural Resources, Illinois State Geological Survey Division, 1980.
MLA (9th ed.) CitationWillman, H. B., and John C. Frye. The Glacial Boundary in Southern Illinois. Illinois Institute of Natural Resources, Illinois State Geological Survey Division, 1980.
Warning: These citations may not always be 100% accurate.