Toomprasen, T., C. Thinvongpituk, and S. Talangkun. “The Study on the Properties of AISI 4140 and AISI 1040 Steel Rods Welded by Friction Welding”. Engineering and Applied Science Research, vol. 41, no. 2, Sept. 2014, pp. 201-1, https://ph01.tci-thaijo.org/index.php/easr/article/view/21786.