WLOKA, J.; ROWLEY, B. New aspects of the $L$-condition for elliptic systems. Topological Methods in Nonlinear Analysis, [S. l.], v. 10, n. 2, p. 283–294, 1997. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.1997.033. Acesso em: 27 apr. 2024.