- H. H. Abbas, A. Yu. Savin, “Index of Elliptic Operators Associated with Discrete Groups and Fixed Points”, Math Notes, 116, no. 1-2, 2024, 139

- H.H. Abbas, A.Yu. Savin, “Localized Chern Character and the index of Elliptic Operators Associated with Discrete Groups”, Russ. J. Math. Phys., 31, no. 4, 2024, 785
