1. B.R. Mitchell, European Historical Statistics, 1750–1970 (London, 1975); second edition (extended to 1975), 1980: and third edition (extended to 1988 and International Historical Statistics: Europe 1750–1988, Basingstoke & New York, 1992)
2. W. A. Robson (ed.), Man and the Social Sciences (London, 1972)
3. W. Paul Strassman, Risk and Technological Innovation (Ithaca, NY, 1959), p. 5