https://ij-healthgeographics.biomedcentral.com/articles/10.1186/1476-072X-5-8
https://ij-healthgeographics.biomedcentral.com/articles/10.1186/1476-072X-5-7
https://ij-healthgeographics.biomedcentral.com/articles/10.1186/1476-072X-5-9