Chistikov 1975. Some problems of the taxonomy of scaphopods. Litharev I.M., [Ed]. [Molluscs, their system, evolution and significance in nature. Theses of communications.] Academy of Sciences USSR. Izdatel'stvo 'Nauka', Leningrad 3-242., Institute of Zoology., 1975: 18-21. Chapter pagination: 18-21