Federal Group

HEYL, A.V., BROCK, M.R., JOLLY, J.L. AND WELLS, C.E., 1965 REGIONAL STRUCTURE OF THE SOUTHEAST MISSOURI AND ILLINOIS-KENTUCKY MINERAL DISTRICTS, U.S. GEOLOGICAL SURVEY BULL. 1202-B, P. B1 - B20 .SNYDER, F.G., AND GERDEMANN, P.E., 1968, GEOLOGY OF THE SOUTHEAST MISSOURI LEAD DISTRICT, IN RIDGE, J.D., ED., ORE DEPOSITS IN THE UNITED STATES, 1933/1967: AIME ROCKY MOUNTAIN SERIES, GRATON SALES VOL., P. 326-358.US BUREAU OF MINES, 1972