1. Balks, R. 1935. The iodine question in Westphalia,Landwirtschaftliches Jahrbuch 81, 939–1002 (in German).
2. Boussingault, J.B. 1831. Recherches sur la cause qui produit le Goitre dans les Cordiliéres de la Nouvelle-Grenade,Annal Chimie (Phys) 48, 41–69.
3. Carter, C.W., Coxon, R.V., Parsons, D.S. and Thompson, R.H.S. 1959.Biochemistry in relation to medicine, 3rd edition, pp. 165–166. Longmans, London.
4. Davies, B.E. 1974. Loss-on-ignition as an estimate of soil organic matter,Soil Science Society of America Proceedings 38, 150–151.
5. Day, T.K. and Powell-Jackson, P.R. 1972. Fluoride, water hardness and endemic goitre,The Lancet i, 1135–1138.