| Acorn-worms and sea squirts (Phyla Hemichordata and Urochordata) |
| Knight-Jones, E.W.; Ryland, J.S. (1996). Acorn-worms and sea squirts (Phyla Hemichordata and Urochordata), in: Hayward, P.J. et al. (Ed.) (1995). Handbook of the marine fauna of North-West Europe. pp. 687-711 |
| In: Hayward, P.J.; Ryland, J.S. (Ed.) (1995). Handbook of the marine fauna of North-West Europe Oxford University/Oxford University Press: Oxford. ISBN 0-19-854054-X. XI, 800 pp., meer |
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