QI, Huang; YUJUN, Dong. Limiting cases of asymptotically positive linear conditions and solvability of Sturm-Liouville boundary-value problems of Duffing equations. Topological Methods in Nonlinear Analysis, [S. l.], v. 26, n. 2, p. 367–384, 2005. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.2005.037. Acesso em: 15 mar. 2025.