W. E.  Ritter and Forsyth, R. A., ?Ascidians of the littoral zone of southern California?, University of California Publications in Zoology, vol. 16 (24), pp. 439-512, 1917.

W. E.  Ritter, ?The ascidians collected by the United States Fisheries Bureau Steamer Albatross on the coast of California during the Summer of 1904?, University of California Publications in Zoology, vol. 4(1), pp. 1-52, 1907.