https://ij-healthgeographics.biomedcentral.com/articles/10.1186/1476-072X-10-48
https://ij-healthgeographics.biomedcentral.com/articles/10.1186/1476-072X-10-47
https://ij-healthgeographics.biomedcentral.com/articles/10.1186/1476-072X-10-49
https://ij-healthgeographics.biomedcentral.com/articles/10.1186/1476-072X-10-50