https://ij-healthgeographics.biomedcentral.com/articles/10.1186/1476-072X-8-71
https://ij-healthgeographics.biomedcentral.com/articles/10.1186/1476-072X-8-73
https://ij-healthgeographics.biomedcentral.com/articles/10.1186/1476-072X-8-70
https://ij-healthgeographics.biomedcentral.com/articles/10.1186/1476-072X-8-72