Ivan, Mircea. “Finitely Defined Functionals and Divided Differences”. Rev. Anal. Numér. Théor. Approx. 33, no. 2 (August 1, 2004): 175–181. Accessed March 30, 2025. https://ictp.acad.ro/jnaat/journal/article/view/2004-vol33-no2-art7.