Literature
- Spoel, S. van der 1967. Euthecosomata, a group with remarkable developmental stages (Gastropoda, Pteropoda). J. Noorduyn and Zn, Gorinchem, 375 pp.
Summary (in Dutch also published separately). - Spoel, S. van der 1976c. Pseudothecosomata, Gymnosomata and Heteropoda. Bohn, Scheltema & Holkema, Utrecht. 484 pp. 246 figs.
- Starobogatov, J. I. 1971. Ordo Thecosomata; ordo Gymnosomata; ordo Heteropoda. In: Polevoy Zool. Inst. Akad. Moscou. opredeliteli planktona (without page or figure numbers, not bound, mimiographed). [in Russsian].
- Tesch, J. J. 1908. The Pteropoda of the Leyden museum. Notes Leiden Mus. 29: 181-203, pl. 7.
- Tesch, J. J. 1913c. Mollusca, Pteropoda. In: F. E. Schulze. Das Tierreich. Eine Zusammenstellung und Kennzeichnung der rezenten Tierformen 36. Berlin (Friedberger and Sohn): i-xvi, 1-154, 108 figs.