1. Benton, M.J. and Harper, D.A.T. 1997. Basic palaeontology. Addison Wesley, Longman, Harlow. 342 pp.
2. Briggs, D.E.G and Crowther, P.R. (eds) 1990. Palaeobiology — a synthesis. Blackwell Scientific Publications, Oxford. 583 pp.
3. Fretter, V. and Graham, A. 1976. A functional anatomy of invertebrates. Academic Press, London.
4. Gould, S.J. 1989. Wonderful Life. The Burgess Shale and the nature of history. Hutchinson Radius, London. 347 pp.
5. Lane, N. G. 1986. Life of the past. Bell and Howell Company, Columbus. 326 pp.