NYAMORADI, N.; ZHOU, Y. Existence of solutions for a Kirchhoff type fractional differential equations via minimal principle and Morse theory. Topological Methods in Nonlinear Analysis, [S. l.], v. 46, n. 2, p. 617–630, 2015. DOI: 10.12775/TMNA.2015.061. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.2015.061. Acesso em: 27 jan. 2022.