Armstrong, J. S. (1967). Derivation of theory by means of factor analysis or Tom Swift and his electric factor machine. The American Statistician, 21, 17-21.
2.
Guttman, L. (1955). A generalized simplex for factor analysis. Psychometrika, 20, 173-192.
3.
Hernnstein, R. J. (1971). IQ in the meritocracy. Boston: AtlanticLittle, Brown.
4.
Humphreys, L. G. (1960). Investigation of the simplex. Psychometrika, 25, 313-323.
5.
Humphreys, L. G. (1974). The misleading distinction between aptitude and achievement tests. In D. R. Green (Ed.), The aptitude-achievement distinction. Monterey, CA: CTB/ McGraw-Hill.
