Boyd, R. and P.J. Richerson.1985. Culture and the Evolutionary Process . Chicago: University of Chicago Press.
4.
Johnson, A. and O. Johnson.1988. Time Allocation among the Machiguenga of Shimaa. Cross Cultural Studies in Time Allocation, Vol. 1. New Haven: Human Relations Area Files.
5.
McIver, J.P. and E.G. Carmines.1981. Unidimensional Scaling. Sage University Papers Series on Quantitative Applications in the Social Sciences. Beverly Hills: Sage Publications.