KHACHATRYAN, I. G. ON SOME FORMULAS FOR THE INDEX OF LINEAR BOUNDED OPERATOR. Proceedings of the YSU A: Physical and Mathematical Sciences, Yerevan, Armenia, v. 43, n. 3 (220), p. 3–9, 2009. DOI: 10.46991/PYSU:A/2009.43.3.003. Disponível em: https://pub.ysu.am/index.php/proceedings-phys-math/article/view/vol43_no3_2009_pp003-009. Acesso em: 20 sep. 2024.