1. 1952.Handbook of Chemistry and Physics, 34th Ed, 330Cleveland: Chemical Rubber Publishing Co.
2. Studies on the Industrial Dust Problem: I. Dust Inhalation and Its Relation to Industrial Tuberculosis
3. Hunter , D. 1962.The Diseases of Occupations, 917Boston: Little, Brown and Company.
4. Harrington , D. and Davenport , Sara . 1937.Review of Literature on Effects of Breathing Dusts with Special Reference to Silicosis, 4Washington: Bureau of Mines Bulletin 400, U. S. Department of Interior.
5. Sutherland , C. 1960.Gold, 26New York: McGraw-Hill Book Company.