Sharma S.Applied multivariate techniques. New York: Wiley , 1996.
2.
Campbell DT , Fiske DW.Convergent and discriminant validity by the multitraitmultimethod matrix . Psychological Bulletin1959; 56: 81-105 .
3.
DeVellis RF.Scale development: theory and applications, 2nd edition. Thousand Oaks: Sage , 2003.
4.
Streiner DL , Norman GR.Health measurement scales: a practical guide to their development and use, 3rd edition. Oxford: Oxford University Press , 2003.
