1. Isler, O., 1950. The chemistry of Vitamin A. Chimia 4:103–118.
2. Isler, O., 1970. Developments in the Field of Vitamins. Experientia, 26:225–240.
3. Office of Nutrition, Technical Assistance Bureau Agency for International Development;JC Bauernfeind,1973
4. Bauernfeind, J.C., 1978. Vitamins: Essential Micronutrients for Man, “Encyclopedia of Food Science”, M.S. Peterson and A.H. Johnson, editors, AVI Publishing Co., Westport, Conn., pp. 788–843.
5. De Ritter, E., 1976. Stability Characteristics of Vitamins in Processed Foods. J. Food. Technol., 30(l):48–54.