Vanno, Vitanya, Wannee Kaemkate, and Suwimon Wongwanich. 2016. “Development and validation of the measurement model of group-level positive psychological capital: Composing group-level variables from individual-level data using data aggregation models”. Kasetsart Journal of Social Sciences 37 (1):99-110. https://so04.tci-thaijo.org/index.php/kjss/article/view/242835.