Bunnakkha, C, and C Jarupisitthorn. “Extraction of Tin from Hardhead by Oxidation and Fusion With Sodium Hydroxide”. Journal of Metals, Materials and Minerals 22, no. 1 (June 30, 2012). Accessed December 1, 2021. http://jmmm.material.chula.ac.th/index.php/jmmm/article/view/16.