1. Hennig, W. Phylogenetic Systematics (Univ. Illinois Press, Urbana, 1966).
2. Nelson, G. & Platnick, N. I. Systematics and Biogeography: Cladistics and Vicariance (Columbia Univ. Press, New York, 1981).
3. Hillis, D. M. & Dixon, M. T. in The Hierarchy of Life (eds Fernholm, B., Bremer, K. & Jornvall, H.) 355–367 (Elsevier, Amsterdam, 1989).
4. Miyamoto, M. M. et al. Proc. natn. Acad. Sci. U.S.A. 85, 7627–7631 (1988).
5. Miyamoto, M. M. & Boyle, S. M. in The Hierarchy of Life (eds Fernholm, B., Bremer, K. & Jornvall, H.) 437–450 (Elsevier, Amsterdam, 1989).