| 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 { SMITH, M. C., AND HENKES, W. C., 1970 , THE MINERAL INDUSTRY OF SOUTH DAKOTA IN 1968 , SOUTH DKOTA GEOLOGICAL SURVEY MINERALS REPORT 16 |