1. Carr, L. E., J. L. Nicholson, and J. P. Donohoe, 1982. Litter treatment effect on broiler environment. Amer. Soc. Agric. Eng., Paper No. 82-4057, ASAE, St. Joseph, MI.
2. The influence of graded levels of atmospheric ammonia on chickens;Charles;Br. Poult. Sci.,1966
3. The physiological role of microelements;Georgievskii,1982
4. An experimental study of the toxicity of ferrous gluconate;Hoppe;Am. J. Med. Sci.,1955
5. A review of the toxicity of iron compounds;Hoppe;Am. J. Med. Sci.,1955