@article{MZM_1973_13_3_a17,
     author = {N. Ya. Vilenkin and S. V. Zotikov},
     title = {On cross products of orthonormal systems of functions},
     journal = {Matemati\v{c}eskie zametki},
     pages = {469--480},
     publisher = {mathdoc},
     volume = {13},
     number = {3},
     year = {1973},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1973_13_3_a17/}
}