Ridhwan, J., J. Noor, M. Zakaria, Z. Zulfattah, and M. Hafidzal. “Effect of Heat Treatment on Microstructure and Mechanical Properties of 6061 Aluminum Alloy”. Journal of Engineering and Technology (JET), vol. 5, no. 1, June 2014, pp. 89-98, https://jet.utem.edu.my/jet/article/view/130.