https://ij-healthgeographics.biomedcentral.com/articles/10.1186/1476-072X-9-14
https://ij-healthgeographics.biomedcentral.com/articles/10.1186/1476-072X-9-15
https://ij-healthgeographics.biomedcentral.com/articles/10.1186/1476-072X-9-16
https://ij-healthgeographics.biomedcentral.com/articles/10.1186/1476-072X-9-17