Afthanorhan, W. M. A. B. W. ., S. . Ahmad, and I. . Mamat. “Pooled Confirmatory Factor Analysis (PCFA) Using Structural Equation Modeling on Volunteerism Program: A Step by Step Approach”. International Journal of Asian Social Science, vol. 4, no. 5, May 2014, pp. 642-53, https://archive.aessweb.com/index.php/5007/article/view/2663.