https://bmcfampract.biomedcentral.com/articles/10.1186/1471-2296-7-52
https://bmcfampract.biomedcentral.com/articles/10.1186/1471-2296-7-51
https://bmcfampract.biomedcentral.com/articles/10.1186/1471-2296-7-49
https://bmcfampract.biomedcentral.com/articles/10.1186/1471-2296-7-50