https://ij-healthgeographics.biomedcentral.com/articles/10.1186/1476-072X-10-60
https://ij-healthgeographics.biomedcentral.com/articles/10.1186/1476-072X-10-62
https://ij-healthgeographics.biomedcentral.com/articles/10.1186/1476-072X-10-61
https://ij-healthgeographics.biomedcentral.com/articles/10.1186/1476-072X-10-59