https://bmcpublichealth.biomedcentral.com/articles/10.1186/1471-2458-5-89 https://bmcpublichealth.biomedcentral.com/articles/10.1186/1471-2458-5-82 https://bmcpublichealth.biomedcentral.com/articles/10.1186/1471-2458-5-84 https://bmcpublichealth.biomedcentral.com/articles/10.1186/1471-2458-5-90 https://bmcpublichealth.biomedcentral.com/articles/10.1186/1471-2458-5-88 https://bmcpublichealth.biomedcentral.com/articles/10.1186/1471-2458-5-85 https://bmcpublichealth.biomedcentral.com/articles/10.1186/1471-2458-5-87 https://bmcpublichealth.biomedcentral.com/articles/10.1186/1471-2458-5-86 https://bmcpublichealth.biomedcentral.com/articles/10.1186/1471-2458-5-81 https://bmcpublichealth.biomedcentral.com/articles/10.1186/1471-2458-5-83