Reynolds, Rick; Janice Elvidge, Krista Reynolds eds. (2021). Investigating Ice Age Floods (PDF) 115, 124. National Park Service, U.S. Department of the Interior. Retrieved on 2023-09-16. "Hands-On Science Lessons Adaptable for Grades K -12". p. 117 of document, 115 of PDF. Also used on page 124 of document, 126 of PDF.