GELDER, Stuart R., et al. “Distribution of Native and Exotic Branchiobdellidans (Annelida: Clitellata) on Their Respective Crayfish Hosts in Northern Italy, With the First Record of Native Branchiobdella Species on an Exotic North American Crayfish”. Journal of Limnology, vol. 58, no. 1, Feb. 1999, pp. 20-24, doi:10.4081/jlimnol.1999.20.