1. Windrow Formation of Upper Mississippi Valley region;Andrews,1958
2. Argillic horizons and their significance in England and Wales;Avery,1985
3. Soils and Geomorphology;Birkeland,1984
4. Heavy mineral ratios of Sangamon weathering profiles in Illinois;Brophy;Ill. Geol. Surv. Circ.,1959
5. Rationale for allowing taxonomic classes of frigid Ultisols;Bryant;Soil Surv. Horiz.,1989