PETRYK, H.; THERMANN, K. A yield-vertex modification of two-surface models of metal plasticity. Archives of Mechanics, Warsaw, Poland, v. 49, n. 5, p. 847–863, 1997. DOI: 10.24423/aom.1440. Disponível em: http://am.ippt.gov.pl/index.php/am/article/view/v49p847. Acesso em: 17 jan. 2026.