1. A. Galatik, J. Duda, L. Minarik, Pressure hydrolysis of leather waste with sodium hydroxide, Czech. Patent CS 252, 382 (1988).
2. Bioaccumulation of chromium from tannery wastewater: an approach for chrome recovery and reuse;Aravindhan;Environ. Sci. Technol.,2004
3. CONAMA, Conselho Nacional do Meio Ambiente. Brasília. Resolução no 357, 2005. Diário Oficial 17.05.2005 Ofício no 88.351/83, 6 p., 2005.
4. Mechanism of hexavalent chromium adsorption by persimmon tannin gel;Nakajimaa;Water Res.,2004
5. EIA, Energy Information Administration, World proved reserves of oil and natural gas, most recent estimates, 2009. Disponível em: http://eia.doe.gov/emeu/international/reserves.html.