Calymene lawsoni and allied species from the Silurian of Britain and their stratigraphical significance: IN: D.E.G.Briggs & P.D.Lane, 1983, Trilobites and other early Arthropods. London: Palaeontological Association (Special Papers in Palaeontology no.30) p.69-88 / D.J.SiveterBooks/Monographs