YAP, Leonard Y. H. On the Impossibility of Representing Certain Functions by Convolutions. Mathematica Scandinavica, Berkeley, CA, United States, v. 26, p. 132–140, 1970. DOI: 10.7146/math.scand.a-10972. Disponível em: https://journals.msp.org/mscand/article/view/2353. Acesso em: 25 jul. 2026.