Reference | {Deposit:: 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:: COX, G.H., 1914, LEAD AND ZINC DEPOSITS OF NORTHWESTERN ILLINOIS: ILLINOIS GEOLOGICAL SURVEY BULLETIN 21, 120 P.} |