SARDARIAN, V. T. ESTIMATES FOR EIGENVALUES AND COMPLETENESS OF EIGENFUNCTIONS OF NON SELFADJOINT SEMIELLIPTIC DIFLERENTIAL OPERATORS. Proceedings of the YSU A: Physical and Mathematical Sciences, Yerevan, Armenia, v. 34, n. 2 (193), p. 10–18, 2000. DOI: 10.46991/PYSUA.2000.34.2.010. Disponível em: https://journals.ysu.am/proceedings-phys-math/article/view/vol34_no2_2000_pp010-018. Acesso em: 12 jun. 2026.