Template:Peel 1991

Peel, J. S. Functional Morphology of the Class Helcionelloida Nov., and the Early Evolution of the Mollusca. Simonetta, A. M.; Conway Morris, S (编). The Early Evolution of Metazoa and the Significance of Problematic Taxa. Cambridge University Press. 1991: 157–177. ISBN 978-0-521-40242-2.