Mandić, V., M. Živković, S. Vulović, and T. Marinković. 2004. “FEM Analysis for the Extrusion Process of Tubes Using Porthole Dies”. Advanced Technologies and Materials 29 (1-2):35-43. https://atm-journal.uns.ac.rs/index.php/atm/article/view/jtp.2004.29.1-2.4.