BRÜDERN, Jörg. Ternary additive problems of Waring’s type. Mathematica Scandinavica, Berkeley, CA, United States, v. 68, p. 27–45, 1991. DOI: 10.7146/math.scand.a-12343. Disponível em: https://journals.msp.org/mscand/article/view/1288. Acesso em: 25 jul. 2026.