Šmehlíková, E., R. Samek, and K. Podaný. “Forming Limits of Thin-Walled Pipes”. Advanced Technologies and Materials, vol. 32, no. 1-2, Dec. 2007, pp. 77-85, https://atm-journal.uns.ac.rs/index.php/atm/article/view/jtp.2007.32.1-2.8.