TY  - JOUR
AU  - Rempulska, Lucyna
AU  - Tomczak, Karolina
TI  - On approximation of functions by certain operators preserving $x^2$
JO  - Commentationes Mathematicae Universitatis Carolinae
PY  - 2008
SP  - 579
EP  - 593
VL  - 49
IS  - 4
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/CMUC_2008__49_4_a4/
LA  - en
ID  - CMUC_2008__49_4_a4
ER  -