_:nb141e0c604224b9b941533e83931eec3xb1
<http://schema.org/image>
<https://static-content.springer.com/image/art%3A10.1186%2F1471-2458-9-181/MediaObjects/12889_2009_Article_1584_Fig1_HTML.jpg>
<https://bmcpublichealth.biomedcentral.com/articles/10.1186/1471-2458-9-181>