WALTER, Johann. Note on a Paper by Stetkær-Hansen Concerning Essential Selfadjointness of Schroedinger Operators. MATHEMATICA SCANDINAVICA, [S. l.], v. 25, p. 94–96, 1969. DOI: 10.7146/math.scand.a-10943. Disponível em: https://tidsskrift.dk/math/article/view/10943. Acesso em: 14 aug. 2026.