Nor Shahirul Umirah Idris, Noor Syuhadah Subki, Ainul Mardziyyah Che Din. “Evaluation Of Metal Concentrations In Two Aquaculture Pond Systems Containing Catfish Using Principl Component Analysis”. International Journal of Advanced Science and Technology, Vol. 29, no. 9s, May 2020, pp. 1724 -29, http://sersc.org/journals/index.php/IJAST/article/view/13941.