Simorangkir, Michael, 		Yohanes, Yohanes, AND 		Badri, Muftil.
" Effect of Spindle Speed of Bar-Plate Rotary Friction Welding Machine on Joint Interface Area and Hardness Value" <em>Journal of Ocean, Mechanical and Aerospace -science and engineering-</em> [Online], Volume 67 Number 1 (30 March 2023)