MINERAL RESOURCES—SOME GENERAL QUANTITATIVE CONSIDERATIONS
Bastin, Edson S., and McCaskey, H. D., The work on mineral resources done by the U. S. Geological Survey: Min. Res. of the United States for 1918, U. S. Geol. Survey, pt. 1, 1920, p. 3a.
Spurr, J. E., Who owns the earth?: Eng. and Min. Jour., vol. 109, 1920, pp. 389-390.
WATER AS A MINERAL RESOURCE
Mead, Daniel W., Hydrology: McGraw-Hill Book Co., New York, 1919, pp. 447-448, 456.
THE COMMON ROCKS AND SOILS AS MINERAL RESOURCES
A good summary of this subject may be found in Engineering Geology, by H. Ries and T. L. Watson, Wiley and Sons, 2d ed., 1915.
Marbut, Curtis F., Soils of the United States: Bull. 96, Bureau of Soils, 1913, p. 10.
THE FERTILIZER GROUP OF MINERALS
Gale, Hoyt S., The potash deposits of Alsace: Bull. 715-B, U. S. Geol. Survey, 1920, pp. 17-55.
Gale, Hoyt S., Potash deposits in Spain: Bull. 715-A, U. S. Geol. Survey, 1920, pp. 1-16.
THE ENERGY RESOURCES—COAL, OIL, GAS (AND ASPHALT)
For more detailed treatment of international coal movements before the war and of coal movements within the United States, see the U. S. Geological Survey's World Atlas of Commercial Geology, Pt. 1, 1921, pp. 11-16.