| 1 | 1. Close,W. Menke, K. H. Selected Topics in animal Nutrition. Manual. 1986 University Hohenheim. |
| 2 | 2. ISO/TC 34/SC 5 - Milk and milk products. Standards catalogue. http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_tc_browse.htm? |
| 3 | 3. Michael H. Tunick,Samuel A. Palumbo,Pina M. Fratamico. 1999.New Techniques in the Analysis of Foods. Kluwer Academic ISBN 0-306-46035- |
| 4 | 4. Glick, V. Methods of biochemical analysis. |