Abd Karim, M. R., M. Asutay, Z. Shafii, and M. Mohd Aris. “Examining Islamic Funds Underperformance: The Case of Malaysia”. The Journal of Muamalat and Islamic Finance Research, vol. 10, no. 1, Jan. 2013, pp. 125-43, https://jmifr.usim.edu.my/index.php/jmifr/article/view/157.