@article{00039577, title = {Approximation by double Walsh polynomials.}, journal = {International Journal of Mathematics and Mathematical Sciences}, volume = {15}, year = {1992}, pages = {209-220}, doi = {10.1155/S0161171292000279}, zbl = {0817.42014}, language = {en}, url = {http://dml.mathdoc.fr/item/00039577} }
Móricz, Ferenc. Approximation by double Walsh polynomials.. International Journal of Mathematics and Mathematical Sciences, Tome 15 (1992) pp. 209-220. doi : 10.1155/S0161171292000279. http://gdmltest.u-ga.fr/item/00039577/