KONDRATIEV, Yu. G.; SILVA, J. L.; STREIT, L. Generalized Appell systems. Methods of Functional Analysis and Topology, [S. l.], v. 3, n. 3, p. 28–61, 1997. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/42. Acesso em: 19 dec. 2025.