@article{1077477034, author = {Rudin, Walter}, title = {$L^2$ -approximation by partial sums of orthogonal developments}, journal = {Duke Math. J.}, volume = {19}, number = {1}, year = {1952}, pages = { 1-4}, language = {en}, url = {http://dml.mathdoc.fr/item/1077477034} }
Rudin, Walter. $L^2$ -approximation by partial sums of orthogonal developments. Duke Math. J., Tome 19 (1952) no. 1, pp. 1-4. http://gdmltest.u-ga.fr/item/1077477034/