PURMONEN, V. T. On quasi-parabolic problems with normal boundary conditions. Annales Fennici Mathematici, [S. l.], v. 7, n. 2, p. 279–290, 1982. DOI: 10.5186/aasfm.1982.0726. Disponível em: https://afm.journal.fi/article/view/134447. Acesso em: 25 nov. 2024.