PURMONEN, V. T. On a complete initial-boundary value problem for parabolic pseudo-differential operators. MATHEMATICA SCANDINAVICA, [S. l.], v. 67, p. 97–118, 1990. DOI: 10.7146/math.scand.a-12323. Disponível em: https://www.mscand.dk/article/view/12323. Acesso em: 6 may. 2024.