1938
United States Geological Survey, 1619
United States Geological Survey, 1937
United States Geological Survey, 1941
United States Geological Survey, 1942
United States Geological Survey, 1935
United States Geological Survey, 1939
United States Geological Survey, 1936
United States Geological Survey
United States Geological Survey, 1770
United States Geological Survey, 1943
