POP, M., and D. FRUNZA. “EXPERIMENTAL AND FINITE ELEMENT ANALYSIS REGARDING THE INFLUENCE OF FRICTION CONDITIONS ON MATERIAL FLOW IN METAL FORMING PROCESSES”. Studia Universitatis Babeș-Bolyai Physica, vol. 60, no. 2, Dec. 2015, pp. 77-88, http://193.231.18.162/index.php/subbphysica/article/view/5941.