Branas, Charles C., Rose A. Cheney, John M. Macdonald, Vicky W. Tam, Tara D. Jackson, and Thomas R. Ten Have. “A Difference-in-Differences Analysis of Health, Safety, and Greening Vacant Urban Space.” American Journal of Epidemiology 174, no. 11 (November 2011): 1296–1306. https://doi.org/10.1093/aje/kwr273.