SPARR, Gunnar. A new proof of Löwner’s theorem on monotone matrix functions. MATHEMATICA SCANDINAVICA, [S. l.], v. 47, p. 266–274, 1980. DOI: 10.7146/math.scand.a-11889. Disponível em: https://tidsskrift.dk/math/article/view/11889. Acesso em: 14 aug. 2026.