Marija Milojevic Stojan Radenovic Bozidar Rosic Jensen's functional and polynomials in several variables. 3322-3329 2011 61 Comput. Math. Appl. 11 https://doi.org/10.1016/j.camwa.2011.04.031 db/journals/cma/cma61.html#MilojevicRR11