@article{GDZPPN002288397,
title = {Approximation Theorems for Semi-Groups of Bounded Linear Transformations.},
journal = {Mathematische Annalen},
volume = {141},
year = {1960},
pages = {256-262},
zbl = {0094.30602},
url = {http://dml.mathdoc.fr/item/GDZPPN002288397}
}
Butzer, P.L.; TILLMANN, H.G. Approximation Theorems for Semi-Groups of Bounded Linear Transformations.. Mathematische Annalen, Tome 141 (1960) pp. 256-262. http://gdmltest.u-ga.fr/item/GDZPPN002288397/