@article{MS2_1967__21_166000,
     author = {Henry Helson and Donald Sarason},
     title = {Past and {Future}},
     journal = {Mathematica Scandinavica},
     pages = {5--16},
     year = {1967},
     volume = {21},
     zbl = {0241.60029},
     url = {http://geodesic.mathdoc.fr/item/MS2_1967__21_166000/}
}