http://www.diveinfo.com/costarica/opisthobranchia/index.html
http://www.seaslugforum.net/factsheet.cfm?base=borncalc
http://www.medslugs.de/E/Atl-W/Bornella_calcarata.htm
http://slugsite.us/bow/nudwk479.htm
http://www.jaxshells.org/bornella.htm