Literature
- Baltzer, F., 1934. Echiurida. In: Handbuch der Zoologie, zweiter Band. Walter de Gruyter & Co., Berlin und Leipzig. .
- Knight-Jones, E.W. & J.S. Ryland 1990. Priapulida, Sipuncula, Echiura, Pogonophora, and Entoprocta. In: The Marine Fauna of the British Isles and North-West Europe. (ed. P.J. Hayward & J.S. Ryland). Clarendon Press, Oxford.