1. Structure and Function in the Nervous System of Invertebrates 1965
2. CLARKE, J.M., J MORPHOL 2: 253 (1889).
3. Clarkson, E. N. K., Palaeontology 16: 425 (1973).
4. Clarkson, E. N. K., Palaeontology 9: 1 (1966).
5. Clarkson, E. N. K., Palaeontology 10: 603 (1967).