ZHANG, Zhitao, YU, Meng and ZHENG, Xiaotian. Existence of nontrivial solutions to Schrödinger systems with linear and nonlinear couplings via Morse theory. Topological Methods in Nonlinear Analysis. Online. 23 June 2023. Vol. 61, no. 2, pp. 701 - 716. [Accessed 3 July 2024]. DOI 10.12775/TMNA.2022.032.