Che, Guofeng, and Tsung-fang Wu. “Three Positive Solutions for the Indefinite Fractional Schrödinger-Poisson Systems”. Topological Methods in Nonlinear Analysis 62, no. 1 (September 23, 2023): 53–81. Accessed July 3, 2024. https://apcz.umk.pl/TMNA/article/view/46305.