BERDYSHEV, A.S.; RYSKAN, A.R. Boundary value problem for the four-dimensional Gellerstedt equation. Bulletin of the Karaganda University. Mathematics Series, [S. l.], v. 104, n. 4, p. 35–48, 2021. DOI: 10.31489/2021m4/35-48. Disponível em: https://mts.buketov.edu.kz/index.php/mathematics-vestnik/article/view/460. Acesso em: 4 jul. 2025.