BELTITA, Ingrid; MELIN, Anders. Analysis of the quadratic term in the backscattering transformation. Mathematica Scandinavica, Berkeley, CA, United States, v. 105, n. 2, p. 218–234, 2009. DOI: 10.7146/math.scand.a-15116. Disponível em: https://journals.msp.org/mscand/article/view/581. Acesso em: 24 jul. 2026.