PLONKA, Ernest. On a Non-Abelian Variety of Groups which are Symmetric Algebras. MATHEMATICA SCANDINAVICA, [S. l.], v. 74, p. 184–190, 1994. DOI: 10.7146/math.scand.a-12488. Disponível em: https://tidsskrift.dk/math/article/view/12488. Acesso em: 13 aug. 2026.