PROSKURIN, D. P. Stability of special class of $q_{ij}$-CCR and extensions of irrational rotation algebras. Methods of Functional Analysis and Topology, [S. l.], v. 6, n. 3, p. 97–104, 2000. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/127. Acesso em: 17 dec. 2025.