Yunus, Norhanishah Mohamad, and Rusmawati Said. “Do Higher Levels of Qualification Lead to Higher Returns to Education: Evidence from Malaysian Education Sector”. International Journal of Economics and Financial Issues, vol. 6, no. 6S, Oct. 2016, pp. 20-26, https://econjournals.net.tr/index.php/ijefi/article/view/3104.