ROMASHCHENKO, G. S. Spectral analysis of positive powers of the integration operator in Sobolev spaces. Methods of Functional Analysis and Topology, [S. l.], v. 10, n. 1, p. 63–74, 2004. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/232. Acesso em: 17 dec. 2025.