1. Hall, J., N.Y. Geol. Surv., Palaeont., 3 (1859).
2. Dana, J. D., Amer. J. Sci., 5, 423; 6, 6 (1873).
3. George, T. N., Proc. Yorks. Geol. Soc., 31, 227 (1958).
4. Johnson, G. A. L., C.R. Fourth Intern. Cong. Start. Geol. Carb., Heerlen, 2, 323 (1962).
5. Trotter, F. M., and Hollingworth, S. E., The Geology of the Brampton District, Mem. Geol. Surv. U.K. (1932).