Zinc and Lead Deposits of Northern Arkansas, by George I. Adams, Assisted by A.H. Purdue and E.F. Burchard, with a Section on the Determination and Correlation of Formations by E.O. Ulrich. [U.S. Geological Survey Professional Paper No. 24. Series A, Economic Geology, 31. Series C, Systematic Geology and Paleontology, 66.].
