Voir la notice de l'article provenant de la source Czech Digital Mathematics Library
@article{ARM_1982__18_1_a3, author = {Neuman, Franti\v{s}ek}, title = {Functions of the form $\sum_{i=1} ^N f_i(x) g_i(t)$ in $L_2$}, journal = {Archivum mathematicum}, pages = {19--22}, publisher = {mathdoc}, volume = {18}, number = {1}, year = {1982}, mrnumber = {683342}, zbl = {0506.41016}, language = {en}, url = {http://geodesic.mathdoc.fr/item/ARM_1982__18_1_a3/} }
Neuman, František. Functions of the form $\sum_{i=1} ^N f_i(x) g_i(t)$ in $L_2$. Archivum mathematicum, Tome 18 (1982) no. 1, pp. 19-22. http://geodesic.mathdoc.fr/item/ARM_1982__18_1_a3/