de Albuquerque, José Carlos, et al. “Positive Ground States for a Subcritical and Critical Coupled System Involving Kirchhoff-Schrödinger Equations”. Topological Methods in Nonlinear Analysis, vol. 53, no. 1, Feb. 2019, pp. 291-07, https://apcz.umk.pl/TMNA/article/view/TMNA.2019.004.