Ghifary Fachrizal Ridlo Arifin, Djoko Sihono Gabriel. “Desıgn Crıterıa For Materıal Value Conservatıon Of Flexıble Plastıc Packagıng”. International Journal of Advanced Science and Technology, Vol. 29, no. 7, May 2020, pp. 88 -97, http://sersc.org/journals/index.php/IJAST/article/view/13171.