Papageorgiou, N. S., V. D. Radulescu, and D. D. Repovs. “Resonant Robin Problems Driven by the P-Laplacian Plus an Indefinite Potential”. Annales Fennici Mathematici, vol. 43, no. 1, Feb. 2018, pp. 483-08, doi:10.5186/aasfm.2018.4331.