| Reference | {Deposit:: F1 < CALVIN, SAMUEL, AND BAIN, H. F., 1900, GEOLOGY OF DUBUQUE COUNTY, IOWA: IOWA GEOLOGICAL SURVEY REPORT [1899], V. 10, P. 379-622.}{Deposit:: F2 < HEYL, A. V., AGNEW, A. F., LYONS, E. J., AND BEHRE, C. H., JR., 1959, THE GEOLOGY OF THE UPPER MISSISSIPPI VALLEY ZINC-LEAD DISTRICT: U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 309, 310 P.} |