1. Robards, K. and Worsfold, P., Analyst, 1991, vol. 116, p. 549.
2. Miller, G.T., Jr., Living in the Environmental Concepts, Problems and Alternatives, Berlmont: Wadsworth Publishing Company Inc., 1975.
3. Alan, S.H., The Encyclopedia Americana, 1984, no. 12 (4), pp. 451–461.
4. Hathaway, G.J, Proctor, N.H, Hughes, J.P., Fischman, M.L. Proctor and Hughes’ Chemical Hazards of The Woreplace, 3rd ed., New York: Van Nostrand Reinhold, 1991.
5. ACGIH [1991], Documentation of the Threshold Limit Values and Biological Exposure Indices, 6th ed., Cincinnati, OH: American Conference of Governmental Industrial Hygienists.