Hou & Bergstrom 1991. The arthropods of the Lower Cambrian Chengjiang fauna, with relationships and evolutionary significance. Simonetta, A.M.; Conway Morris, S.[Eds]. The early evolution of Metazoa and the significance of problematic taxa. Proceedings of an International Syposium held at the University of Camerino 27- 31 March 1989., Cambridge University Press, Cambridge, New York etc., 1991: 179-187. Chapter pagination: 179-187