Bui Khac Khanh, and Nguyen Thanh Phu. “RESEARCHING ON EFFECT OF d/D AND H/D RATIOS TO MACHING FORCE IN BACKWARD EXTRUSION TECHNOLOGY FOR PIPE PARTS FROM HIGH - STRENGTH LOW ALLOY - STEEL”. Journal of Applied Science and Technology, Vol. 43, Sept. 2024, pp. 52-27, http://tapchi.utehy.edu.vn/index.php/jst/article/view/731.