For citations:

Romanencko V.P., Sizov D.V., Illarionov G.P. HOLLOW BILLET PUNCH PIERCING PROCESS GEOMETRY PARAMETERS EXPERIMENTAL STUDY. Izvestiya. Ferrous Metallurgy. 2012;55(11):31-34. (In Russ.) https://doi.org/10.17073/0368-0797-2012-11-31-34