Alheta, Saleh, Sayed Zayan, Tamer Mahmoud, and Attia Gomaa. 2016. “Optimization of Friction Stir Spot Welding Process Parameters for AA6061-T4 Aluminium Alloy Plates”. American Scientific Research Journal for Engineering, Technology, and Sciences 20 (1):244-53. https://asrjetsjournal.org/index.php/American_Scientific_Journal/article/view/1779.