BEREZANSKY, Yu. M.; GEKHTMAN, M. I. Inverse problem of spectral analysis and the non-Abelian chains of nonlinear equations . Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 42, n. 6, p. 730–747, 1990. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/8829. Acesso em: 6 dec. 2025.