GOR'KAVYI, V. A.; NEVMERZHITSKAYA, E. N. Two-dimensional pseudospherical surfaces with degenerate Bianchi transformation. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 63, n. 11, p. 1460–1468, 2011. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2818. Acesso em: 6 dec. 2025.