Loeblich, A. R., Tappan, H. N., 1987: Foraminiferal genera and their classification. Van Nostrand, Reinhold Co. New York 1728 pp. Plate 323, Figs. 9-10: U. Carboniferous, Pennsylvanian, Oklahoma, USA. Top and side views, x 63 (from Loeblich and Tappan, 1964).