Md. Yasin, M. A. S. bin, M. N. bin Daud, H. bt. Musa, and S. S. Imam. “ffect of eaningfulness of earning eterials on peed of earning”. he ournal of ehavioral cience, ol. 3, no. 1, 1, pp. 26-30, https://so06.tci-thaijo.org/index.php/IJBS/article/view/2160.