APA Edition Citation

Butzer, P. L., & Berens, H. (1967). Semi groups of operators and approximation. Springer-Verlag.

Chicago Edition Citation

Butzer, Paul L., and Hubert Berens. Semi Groups of Operators and Approximation. New York: Springer-Verlag, 1967.

MLA Edition Citation

Butzer, Paul L., and Hubert Berens. Semi Groups of Operators and Approximation. Springer-Verlag, 1967.