| Reference | {Deposit:: SCHWARTZ, G. ET AL, 1959, INVESTIGATION OF THE COMMERCIAL POSSIBILITIES OF MARL IN MINNESOTA, OFFICE OF IRON RANGE RESOURCES AND REHABILITATION.}{Deposit:: STAUFFER, C.R., AND G.A. THIEL, 1933, THE LIMESTONES AND MARLS OF MINNESOTA, MINNESOTA GEOLOGICAL SURVEY BULL 23.} |