Nowak, Oliver. “Korovkin-Type Convergence Results for Multivariate Shepard Formulae”. Rev. Anal. Numér. Théor. Approx. 38, no. 2 (August 1, 2009): 170–176. Accessed April 11, 2025. https://ictp.acad.ro/jnaat/journal/article/view/2009-vol38-no2-art7.