http://echinoblog.blogspot.fr/2012/01/how-to-tell-apart-knobby-stars.html|titre=How to tell apart the "knobby stars" Protoreaster from Pentaceraster (fr)
http://www.wildsingapore.com/wildfacts/echinodermata/asteroidea/cfbigstars.htm|titre=Big sea stars : how to tell them apart ? (fr)