1. Bartholomew, G. A., Ideas on Human Evolution, Selected Essays, 1949-1961: 378 (1967).
2. Campbell, B., Human Evolution: 203 (1966).
3. CAVAGNA, G.A., MECHANICAL WORK IN RUNNING, JOURNAL OF APPLIED PHYSIOLOGY 19: 249 (1964).
4. Napier, J., Classification and Human Evolution: 186 (1963).
5. NAPIER, J.R., ANTIQUITY OF HUMAN WALKING, SCIENTIFIC AMERICAN 216: 56 (1967).