PIGNO, Louis. Transforms vanishing at infinity in a certain direction and semi-idempotent measures. Mathematica Scandinavica, Berkeley, CA, United States, v. 41, p. 153–158, 1977. DOI: 10.7146/math.scand.a-11709. Disponível em: https://journals.msp.org/mscand/article/view/1939. Acesso em: 25 jul. 2026.