Abdullaev, J. I., Khalkhuzhaev, A. M., & Kuliev, K. D. (2022). The existence of eigenvalues of Schrödinger operator on three dimensional lattice. Methods of Functional Analysis and Topology, 28(3), 189-208. https://doi.org/https://doi.org/10.31392/MFAT-npu26_3.2022.01