Cabada, A. ., and R. Khaldi. “Lyapunov-Type Inequality for Higher Order Left and Right Fractional P-Laplacian Problems”. Proyecciones (Antofagasta, On Line), vol. 40, no. 4, Aug. 2021, pp. 1031-40, doi:10.22199/issn.0717-6279-4366.