CUMMINGS J B REPT OF S D STATE PLANNING BOARD TIN DEPOSITS O1936 P 24CUMMINGS J B REPT OF S D STATE PLANNING BOARD TUNGSTEN MININD P 24S DAK BUREAU MINES INF CIRC 7069 1939 P 35 36USGS BULL 380 P 142-143S DAK SCHOOL OF MINES BULL 17 P123S DAK SCHOOL OF MINES BULL 12 P 61-62U S BUREAU OF MINES INF CIRC 7707 P 50