http://www.seaslugforum.net/showall/bullvitr
http://vieoceane.free.fr/mollusques/Bullinidae.htm
http://gastropods.com/1/Shell_32111.shtml
http://www.seaslugsofhawaii.com/species/Bullina-vitrea-a.html
http://www.umiushi-zukan.com/eng/list_pic.php?ssw=g&kind_id=506