Djeffal, S. H., and A. Benselhoub. “Research of the Fučik Spectrum for the (p,q)-Laplacian Operator by Min-Max Theory”. Technology Audit and Production Reserves, vol. 3, no. 2(71), Apr. 2023, pp. 30-35, doi:10.15587/2706-5448.2023.277565.