Tshwane. [2008-10-19]. (原始内容存档于2008-10-15). Marais, Riaan. A Plant EcologicalStudy of the Rietvlei Nature Reserve, Gauteng Province (PDF). City of Tshwane
2011) (3): 305–29. doi:10.1525/sp.2011.58.3.305. This study examines the role of "ecological threat" in shaping the U.S. environmental movement. … Declines
and socio-economic determinants of infant mortality in Poland: an ecologicalstudy. Environmental Health. July 2015, 14: 61. PMC 4508882 . PMID 26195213