http://rfbolland.com/okislugs/volvange.html
http://www.seaslugforum.net/showall/volvange
http://www.nudibranch.com.au/pages/2242e.htm
http://www.underwaterkwaj.com/nudi/sacoglossans/e029.htm
http://sacoglossa.lifedesks.org/node/69
http://www.nudipixel.net/species/volvatella_angeliniana/
http://www.umiushi-zukan.com/eng/list_pic.php?ssw=g&kind_id=51