TY  - DATA
AU  - K. Donner
TI  - Extension of Positive Operators and Korovkin Theorems
T2  - Lecture Notes in Mathematics
SN  - 9783540389699
PY  - 1982///
CY  - Heidelberg
PB  - Springer Berlin
KW  - Mathematics and Statistics
UR  - https://doi.org/10.1007/BFb0094133
ER  -