L. Ramskold et Edgecombe G.d, Revision of the Silurian encrinurine trilobite Wallancia LAMONT 1978, with species from Gotland and Canada, Palaontologische Zeitschrift Palaontologische Zeitschrift (Print);Journal of Palaontologische Gesellschaft Scientific contributions to palaeontology, 68(1/2), 1994, pp. 89-115