Illustration(link is external) from Wikimedia Commons by Blausen.com staff (2014). "Medical gallery of Blausen Medical 2014(link is external)". WikiJournal of Medicine 1 (2). DOI(link is external): 10.15347/wjm/2014.010(link is external). ISSN(link is external) 2002-4436(link is external) / CC BY 3.0(link is external)