1. Carroll JD (1972) Individual differences and multidimensional scaling. In: Shepard RN, Romney AK, Nerlove SB, Multidimensional scaling: Theory and Applications in the Behavioural sciences. Seminar Press, London, pp 105–155
2. Dayhoff MO, Eck RV, Park CM (1972) A model of evolutionary change in proteins. In: Dayhoff MO (ed) Atlas of protein sequence and structure. National Biomedical Research Foundation, Georgetown University, Washington DC, pp 89–99
3. Dickerson KE, Geis I (1969) The structure and action of proteins. Harper and Row, New York
4. Guttmann L (1968) A general non-metric technique for finding the smallest co-ordinate space for a configuration of points. Psychometrika 33:469–506
5. Jorre RP, Curnow RN (1975) A model for the evolution of proteins. Biochimie 57:1147–1156