BRONDSTED, Arne. On the Subdifferential of the Supremum of Two Convex Functions. MATHEMATICA SCANDINAVICA, [S. l.], v. 31, p. 225–230, 1972. DOI: 10.7146/math.scand.a-11428. Disponível em: https://tidsskrift.dk/math/article/view/11428. Acesso em: 14 aug. 2026.