1. Marco Polo, in The Travels of Macro Polo, p.81, Chapter 43, Livenight, New York, 1926.
2. RJ. Magee and B.D. James, “Selenium”, in Handbook on Metals in Clinical Chemistry. H. G. Seiler, A. Sigel and H. Sigel (eds), Marcel Dekker, New York, 1993.
3. RA Zingaro and W.C. Cooper (eds), Selenium, Van Nostrand-Reinhold Co., New York, 1974.
4. N.N. Greenwood and A. Eamshaw, Chemistry of the Elements, Pergamon Press, Oxford, Chapter 16, 1984.
5. J. Alexander, J. Hogberg, Y. Thomassen and J. Aaseth, “Selenium”, in Handbook ofToxicity of Inorganic Compounds. H.G. Seiler, H. Sigel (eds), Marcel Dekker, New York, Chapter 53, 1988.