NIFTULLAYEVA, Sh. Necessary conditions for solutions for the mixed type equations. Bulletin of Taras Shevchenko National University of Kyiv. Physics and Mathematics, [S. l.], n. 2, p. 103–108, 2021. DOI: 10.17721/1812-5409.2021/2.14. Disponível em: https://bphm.knu.ua/bphm/article/view/273. Acesso em: 7 nov. 2026.