Sapaw, Rohana, brahim Ahmad, Azami Zaharim, Asban Dolah, Siti Kudnie Sahar, and Nordiana Rajaee. 2005. “E-Beam Metallization and Optimization Using Second-Order Single Response Surface Methodology”. Malaysian Journal of Science 24 (2):97-108. https://ajba.um.edu.my/index.php/MJS/article/view/8349.