TSUTSULIAN, A. V. BOUNDARY PROBLEMS FOR HIGH ORDER DEGENERATE QUASILINEAR EQUATIONS. Proceedings of the YSU A: Physical and Mathematical Sciences, Yerevan, Armenia, v. 36, n. 1 (197), p. 24–33, 2002. DOI: 10.46991/PYSUA.2002.36.1.024. Disponível em: https://journals.ysu.am/index.php/proceedings-phys-math/article/view/vol36_no1_2002_pp024-033. Acesso em: 21 jan. 2026.