Chronologic evidence for multiple periods of loess deposition during the Late Pleistocene in the Missouri and Mississippi River Valley, United States: Implications for the activity of the Laurentide ice sheet - Forman, S.L.; Bettis III, E. Arthur; Kemmis, T.J.; Miller, B.B. (Palaeogeography, Palaeoclimatology, Palaeoecology, 1992)