OKAYASU, Rui. $C^*$-algebras associated with the fundamental groups of graphs of groups. MATHEMATICA SCANDINAVICA, [S. l.], v. 97, n. 1, p. 49–72, 2005. DOI: 10.7146/math.scand.a-14963. Disponível em: https://tidsskrift.dk/math/article/view/14963. Acesso em: 14 aug. 2026.