Takane, Marina, Shizu Yabe, Yumiko Tateshita, Yusuke Kobayashi, Akihiko Hino, Kazuo Isono, Hiromasa Okayasu, Ousmane Diop, and Takeo Tadono. “Satellite Imagery Technology in Public Health: Analysis of Site Catchment Areas for Assessment of Poliovirus Circulation in Nigeria and Niger”. Geospatial Health 11, no. 3 (November 21, 2016). Accessed May 25, 2019. https://geospatialhealth.net/index.php/gh/article/view/462.