Costello, A. B., & Osborne, J. W. (2005). Best Practices in Exploratory Factor Analysis:
Four recommendations for getting the most from your analysis. Practical Assessment, Research, and Evaluation, 10(7), 1-9.
Osborne, J. W., & Costello, A. B. (2004). Sample size and subject to item ratio in
principal components analysis. Practical Assessment, Research & Evaluation, 9(11), 8.