P. L. Butzer
Karl der Grosse und sein Nachwirken, 1200 Jahre Kultur und Wissenschaft in Europa =
Anniversary Volume on Approximation Theory and Functional Analysis
Linear Operators and Approximation II / Lineare Operatoren und Approximation II
Abstract Spaces and Approximation / Abstrakte Raume und Approximation
Fourier Analysis and Approximation
Functional Analysis and Approximation
On Approximation Theory (International Series of Numerical Mathematics)
On Bernstein polynomials