@article{MAN_1923__90_159014,
     author = {J.L. Walsh},
     title = {A property of {Haar's} system of orthogonal functions.},
     journal = {Mathematische Annalen},
     pages = {38--45},
     publisher = {mathdoc},
     volume = {90},
     year = {1923},
     zbl = {49.0293.02},
     url = {http://geodesic.mathdoc.fr/item/MAN_1923__90_159014/}
}