BARANOVICH, A. M.; DALETSKII, Yu. L. Differential-geometric relations for a class of formal operator power series. Methods of Functional Analysis and Topology, [S. l.], v. 2, n. 1, p. 1–16, 1996. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/6. Acesso em: 19 dec. 2025.