Draganov, B. “Strong Converse Inequalities for the Weighted Multivariate Bernstein-Durrmeyer Operator on the Simplex via Multipliers”.
Ann. Sofia Univ. Fac. Math. And Inf.
, vol. 105, Dec. 2018, pp. 55-73, doi:10.60063/gsu.fmi.105.55-73.