BioPortal. Environment Ontology [online]. 2005-. The National Center for Biomedical Ontology is one of the National Centers for Biomedical Computing supported by the NHGRI, the NHLBI, and the NIH Common Fund under grant U54-HG004028. Board of Trustees of Leland Stanford Junior University. http://bioportal.bioontology.org/ (11 October 2013).

BioPortal. Environment Ontology [online]. 2005-. The National Center for Biomedical Ontology is one of the National Centers for Biomedical Computing supported by the NHGRI, the NHLBI, and the NIH Common Fund under grant U54-HG004028. Board of Trustees of Leland Stanford Junior University. http://bioportal.bioontology.org/ (11 October 2013).