Plančak M, Bramley A, Osman F. Investigation of plane-strain backward extrusion process by means of upper bound method. J Prod Eng [Internet]. 1989 Dec. 1 [cited 2024 Nov. 22];6(5, 6):87-9. Available from: http://sp.ftn.uns.ac.rs/index.php/jpe/article/view/814