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References:

Vehkalahti, Kimmo & Puntanen, Simo & Tarkkonen, Lauri (2007). Effects of
    measurement errors in predictor selection of linear regression model.
    Computational Statistics & Data Analysis, 52(2), 1183-1195.
    http://dx.doi.org/10.1016/j.csda.2007.05.005 

Tarkkonen, L. & Vehkalahti, K. (2005). Measurement errors in multivariate
    measurement scales. Journal of Multivariate Analysis, 96(1), 172-189.
    http://dx.doi.org/10.1016/j.jmva.2004.09.007 

Vehkalahti, Kimmo (2000). Reliability of Measurement Scales: Tarkkonen's
    general method supersedes Cronbach's alpha. Statistical Research
    Reports 17, Finnish Statistical Society, Helsinki, Finland.

Tarkkonen, Lauri (1987). On Reliability of Composite Scales. Statistical
    Studies 7, Finnish Statistical Society, Helsinki, Finland.

Cronbach, L. J. (1951). Coefficient alpha and the internal structure of tests.
    Psychometrika, 16, 297-334.
  M = More information on reliability of measurement scales