http://slugsite.us/bow/nudwk211.htm
http://slugsite.us/bow/hal_3a.htm
http://www.medslugs.de/E/Ind-E/Halgerda_stricklandi/Selection.htm
http://www.seaslugforum.net/showall/halgstric
http://www.nudipixel.net/species/halgerda_stricklandi/
http://www.umiushi-zukan.com/eng/list_pic.php?ssw=g&kind_id=1322