1. Ball, I. R., 1973a. On the anatomy and affinities of Nesion arcti-cum Hyman, a marine triclad from Alaska (Platyhel-minthes, Turbellaria). Can. J. Zool. 51: 1299–1305.
2. Ball, I. R., 1973b. A new species of marine triclad Turbellarian of the genus Sabussowia from Prince Edward Island. J. Fish. Res. Bd Can. 30: 389–394.
3. Ball, I. R., 1975. Contributions to a revision of the marine triclads of North America: the monotypic genera Nexilis, Nesion, and Foviella (Turbellaria, Tricladida). Can. J.. Zool. 53: 395–407.
4. Ball, I. R., 1977a. La faune terrestre de I’Île de Sainte-Hélène VI-2. Turbellaria. Ann. Mus. r. Afr. Centr. in-8, Zool. 220: 492–511.
5. Ball, I. R., 1977b. On the phylogenetic classification of aquatic planarians. Acta Zool. fenn. 154: 21–35.