1. On two dimensional Bernstein polynomials;Butzer;Can. J. Math.,1953
2. On a generalization of Bernstein polynomials;Cheney;Rev. Math. Univ. Parma,1964
3. Direct and inverse theorems for Szász–Lupaş type operators in simultaneous approximation;Deo;Mat. Vesnik.,2006
4. Direct estimate for Bernstein polynomials;Ditzian;J. Approx. Theory,1994
5. Approximations by polynomials in C[-1,1];Ditzian;Can. J. Math.,1992