HEIKKILÄ, S. On the method of successive approximations for Volterra integral equations. Annales Fennici Mathematici, [S. l.], v. 1, n. 1, p. 39–47, 1975. DOI: 10.5186/aasfm.1975.0103. Disponível em: https://afm.journal.fi/article/view/134241. Acesso em: 14 may. 2024.