1. Llandovery conodonts from the Welsh Borderland;Aldridge R. J.;Bull. Br. Mus. Nat. Hist. (Geol.),1972
2. Anonymous 1964: British Palaeozoic Fossils. Br. Mus. Nat. Hist. 208 pp. London.
3. A Sagitta Zone Conodont Fauna from the Wenlockian of the Usk Inlier, Monmouthshire;Austin R. L.;Geol. Mag.,1967
4. Lower Paleozoic Conodont Provincialism;Barnes C. R.;Geol. Soe. Am. Spee. Paper,1973
5. A new stage for orienting microfossils;Barnett S. G.;J. Paleont.,1970