LAHUTA, V. V. Grade compulations on Paret’s set with two indexes. Science and Transport Progress , [S. l.], n. 38, p. 194–200, 2011. DOI: 10.15802/stp2011/6838. Disponível em: https://stp.ust.edu.ua/article/view/6838. Acesso em: 9 apr. 2025.