http://www.seaslugforum.net/showall/bullampu
http://www.conchology.uunethost.be/GENERAL/Cyberconchology/SuperConch/Gastropoda/BULLIDAE.html
http://rfbolland.com/okislugs/bullampu.html
http://www.medslugs.de/E/Ind-SW/Bulla_ampulla/Selection.htm
http://www.medslugs.de/E/Pac-W/Bulla_ampulla/Selection.htm
www.Philippine-Sea-Slugs.com/Cephalaspidea/Bulla_ampulla.htm
http://www.gastropods.com/4/Shell_14.html
http://www.underwaterkwaj.com/nudi/cephalaspideans/e085.htm
http://www.nudipixel.net/species/bulla_ampulla/
http://www.medslugs.de/E/Ind-E/Bulla_ampulla/Selection.htm
http://www.nmr-pics.nl/Bullidae/album/index.html
http://opistobranquis.info/en/guia/cephalaspidea/bulla-ampulla/
http://www.vibrantsea.net/bulla6704_anilao2017.htm