https://bmcpublichealth.biomedcentral.com/articles/10.1186/1471-2458-4-31
https://bmcpublichealth.biomedcentral.com/articles/10.1186/1471-2458-4-26
https://bmcpublichealth.biomedcentral.com/articles/10.1186/1471-2458-4-30
https://bmcpublichealth.biomedcentral.com/articles/10.1186/1471-2458-4-28
https://bmcpublichealth.biomedcentral.com/articles/10.1186/1471-2458-4-27
https://bmcpublichealth.biomedcentral.com/articles/10.1186/1471-2458-4-29