YUSENKO, K. A. On existence of $*$-representations of certain algebras related to extended Dynkin graphs. Methods of Functional Analysis and Topology, [S. l.], v. 12, n. 2, p. 197–204, 2006. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/313. Acesso em: 16 dec. 2025.