http://www.seaslugforum.net/showall/costusag
http://rfbolland.com/okislugs/costusag.html
http://slugsite.us/bow/nudwk435.htm
http://www.nudipixel.net/species/costasiella_usagi/
http://www.medslugs.de/E/Ind-E/Costasiella_usagi/Selection.htm
http://www.Philippine-Sea-Slugs.com/Sacoglossa/Costasiella_usagi.htm
http://sacoglossa.lifedesks.org/pages/34161
http://marliwakeling.jalbum.net/Nudibranchs/slides/Costasiella usagi.html
http://www.umiushi-zukan.com/eng/list_pic.php?ssw=g&kind_id=99
http://www.medslugs.de/E/Pac-W/Costasiella_usagi/Selection.htm
http://www.vibrantsea.net/costasiella2301_anilao2013.htm
http://www.medslugs.de/E/Pac-NW/Costasiella_usagi/Selection.htm