VAN GOOL, F. Semiliniear perturbation of linear harmonic maps. Annales Fennici Mathematici, [S. l.], v. 17, n. 2, p. 367–391, 1992. DOI: 10.5186/aasfm.1992.1721. Disponível em: https://afm.journal.fi/article/view/134763. Acesso em: 14 apr. 2025.