| Reference | {Deposit:: F1 < 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.}{Deposit:: F2 < HEYL, A. V., AND WEST, W. S., 1982, OUTLYING MINERAL OCCURRENCES RELATED TO THE UPPER MISSISSIPPI VALLEY MINERAL DISTRICT, WISCONSIN, IOWA, ILLINOIS, AND MINNESOTA: ECONOMIC GEOLOGY, V. 77, P. 1803-1817.} |