BELTITA, I.; MELIN, A. Analysis of the quadratic term in the backscattering transformation. MATHEMATICA SCANDINAVICA, [S. l.], v. 105, n. 2, p. 218–234, 2009. DOI: 10.7146/math.scand.a-15116. Disponível em: https://www.mscand.dk/article/view/15116. Acesso em: 3 may. 2024.