1. Boucot, A. J., Johnson, J. G., and Talent, J. A., Alberta Soc. Petrol. Geol., Internat. Symposium on the Devonian System, Calgary, 1967, 2, 1239 (1967).
2. Boucot, A. J., Johnson, J. G., and Talent, J. A., Geol. Soc. Amer. Spec. Paper 119, 9 (1969).
3. Johnson, J. G., and Boucot, A. J., in Atlas of Palaeobiogeography (edit. by Hallam, A.) (Fig. 1) (Elsevier, 1972).
4. Sloss, L. L., Geol. Soc. Amer. Bull., 74, 93, Fig. 6 (1963).
5. Dearnley, R., in Physics and Chemistry of the Earth (edit. by Ahrens, L. H., et al.), 7, 68 (Pergamon Press, 1966).