| Reference | U. S. GEOLOGICAL SURVEY, U. S. BUREAU OF RECLAMATION, AND SOUTH DAKOTA GEOLOGICAL SURVEY, 1975 , MINERAL AND WATER RESOURCES OF SOUTH DAKOTA, SOUTH DAKOTA GEOLOGICAL SURVEY BULLETIN 16 { PERSSE, F. H., AND HENKES, W. C., 1969 , THE MINERAL INDUSTRY OF SOUTH DAKOTA IN 1967 , SOUTH DAKOTA GEOLOGICAL SURVEY MINERALS REPORT 15 |