TY  - BOOK
AU  - BUTZER, PAUL L
AU  - BERENS, HUBERT
TI  - Semi-Groups of Operators and Approximation
U1  - B27 
PY  - 1967///
CY  - NEW YORK
PB  - Springer Verlag Berlin Heidelberg
KW  -  SCIENCE
KW  - BANACH SPACES
ER  -