Howell, B.F., Bridge, Josiah, Deiss, C.F., Edwards, Ira, Lochman, Christina, Raasch, G.O., and Resser, C.E., assisted by D.C. Duncan, J.F. Mason, and N.M. Denson, 1944, Correlation of Cambrian formations of North America: Geological Society of America Bulletin, v. 55, no. 8, p. 993-1003, 1 sheet.