1. United States Environmental Protection Agency (EPA). 2007. “The national water quality inventory: Report to Congress for the 2002 reporting cycle – a profile”. Washington, DC: US EPA. Fact Sheet No. EPA 841‐F‐07‐003
2. Scott, T.A. and Mercer, E.I. 1996. “Concise Encyclopedia of Biochemistry and Molecular Biology”. Edited by: Jakube, H.D. 245–306. Berlin: W. de Gruyter.