Paltanea R. Approximation Theory Using Positive Linear Operators

Basel: Birkhäuser, 2004. — 207 p.Offers an examination of the multivariate approximation case
Special focus on the Bernstein operators, including applications, and on two new classes of Bernstein-type operators
Many general estimates, leaving room for future applications (e.g. the B-spline case)
Extensions to approximation operators acting on spaces of vector functions
Historical perspective in the form of previous significant results