Gascon M, Cirach M, Martinez D, Dadvand P, Valentin A, Plasencia A, Nieuwenhuijsen MJ. Normalized difference vegetation index (NDVI) as a marker of surrounding greenness in epidemiological studies: the case of Barcelona city. Urban For Urban Green. 2016 Sep;19:88-94. doi: 10.1016/j.ufug.2016.07.001
Pattanayak SK, Poulos C, Yang JC, Patil SR, Wendland KJ. Of taps and toilets: quasi-experimental protocol for evaluating community-demand-driven projects. J Water Health. 2009 Sep 1;7(3):434-51.