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Daley, Paul E. J. The first solute which is attached as an adult: a Mid-Cambrian fossil from Utah with echinoderm and chordate affinities. Zoological Journal of the Linnean Society. 1996, 117 (4): 405–440. ISSN 0024-4082. doi:10.1111/j.1096-3642.1996.tb01659.x.