Semi-groups of operators and approximation,
[by] Paul L. Butzer and Hubert Berens.
APA Citation
Butzer, P. Leo., Berens, H. (1967). Semi-groups of operators and approximation. Berlin: Springer-Verlag.
MLA Citation
Butzer, Paul Leo, 1928-, and Hubert Berens. Semi-groups of Operators And Approximation. Berlin: Springer-Verlag, 1967.
Warning: These citations may not always be complete (especially for serials).