https://ij-healthgeographics.biomedcentral.com/articles/10.1186/1476-072X-6-3
https://ij-healthgeographics.biomedcentral.com/articles/10.1186/1476-072X-6-1
https://ij-healthgeographics.biomedcentral.com/articles/10.1186/1476-072X-6-2