ASPLUND, S. O. Finite Boundary Value Problems Solved by Green’s Matrix. Mathematica Scandinavica, Berkeley, CA, United States, v. 7, p. 49–56, 1959. DOI: 10.7146/math.scand.a-10560. Disponível em: https://journals.msp.org/mscand/article/view/2786. Acesso em: 8 sep. 2026.