Khachatryan IG. ON SOME FORMULAS FOR THE INDEX OF LINEAR BOUNDED OPERATOR. Proc. YSU A: Phys. Math. Sci. [Internet]. 2009 Oct. 4 [cited 2024 Sep. 20];43(3 (220):3-9. Available from: https://pub.ysu.am/index.php/proceedings-phys-math/article/view/vol43_no3_2009_pp003-009