1. AOAC 1984 Official Methods of Analysis. Association of Official Analytical Chemists, Washington, DC, USA, pp 414, 420.
2. 1975 The Mathematics of Diffusion. Clarendon Press, Oxford, UK, pp 58–60.
3. FAO/WHO 1974 Toxicological evaluations of certain food additives with a review of general principles and specifications. FAO (Food and Agriculture Organization of the United Nations), Rome, Italy, p 40.