STETKÆR, Henrik. D’Alembert’s and Wilson’s functional equations for vector and $2\times 2$ matrix valued functions. Mathematica Scandinavica, Berkeley, CA, United States, v. 87, n. 1, p. 115–132, 2000. DOI: 10.7146/math.scand.a-14302. Disponível em: https://journals.msp.org/mscand/article/view/903. Acesso em: 24 jul. 2026.