1. Nutrient Requirements of Poultry;National Research Council,1994
2. Official Methods of Analysis of AOAC International;AOAC,1996
3. Combustion nitrogen analyzer, Elementar Americus Inc., Mt. Laurel, NJ.
4. Tecator-Soxtec fat extractor. Tecator, Herndon, VA.
5. EPA Method Study 27, Method 200.7. EPA-600/S4-85/05;Maxfield,1985