Thurstone, L. L. (1935). The principal axes. In L. L. Thurstone, The vectors of mind: Multiple-factor analysis for the isolation of primary traits (pp. 120-133). Chicago, IL, US: University of Chicago Press.
http://dx.doi.org/10.1037/10018-004
It has been shown that a set of traits may be regarded as n points in a common-factor space of r dimensions. It has also been shown that by rotation of F there exists an infinite number of factorial matrices which reproduce the correlations in R. It is natural to inquire whether a rotational criterion can be found by which a unique solution F may be obtained. This chapter examines one solution which adopts the principal axes as the reference axes of F. (PsycINFO Database Record (c) 2016 APA, all rights reserved)