BioStor
 | Synopsis der oegopsiden Cephalopoden Georg Pfeffer (1900) Mitteilungen aus dem Naturhistorischen Museum 17: 145-198 |
 | Light production in cephalopods. 1. An introductory survey S S Berry (1920) Biological Bulletin. Marine Biological Laboratory (Woods Hole) 38: 141-169 |
 | The identification of cephalopod "beaks" and the relationship between beak size and total body weight Malcolm R Clarke (1962) Bulletin of the British Museum (Natural History). Zoology 8(10): 419-480 |