https://ij-healthgeographics.biomedcentral.com/articles/10.1186/1476-072X-11-5
https://ij-healthgeographics.biomedcentral.com/articles/10.1186/1476-072X-11-4
https://ij-healthgeographics.biomedcentral.com/articles/10.1186/1476-072X-11-6