1. U.S. Environmental Protection Agency, Press Release, May 1, 1999;, December 21, 2000.
2. Federal Register, Vol, 65, No. 28, U.S. Govt. Printing Office, Washington, DC, 2000.
3. Hydrotreating Catalysis, Science and Technology;Topsøe,1991
4. Borides, Silicides and Phosphides;Aronsson,1965