https://ij-healthgeographics.biomedcentral.com/articles/10.1186/1476-072X-6-48
https://ij-healthgeographics.biomedcentral.com/articles/10.1186/1476-072X-6-49
https://ij-healthgeographics.biomedcentral.com/articles/10.1186/1476-072X-6-46
https://ij-healthgeographics.biomedcentral.com/articles/10.1186/1476-072X-6-47