Ryland, J. S., H. de Blauwe, R. Lord, and J. A. Mackie. “Recent Discoveries of Alien Watersipora (Bryozoa) in Western Europe, With Redescriptions of Species”. Zootaxa, vol. 2093, no. 1, May 2009, pp. 43–59, doi:10.11646/zootaxa.2093.1.3.