@article{PM_1990_1990_1_a20,
     author = {Waszak, Aleksander},
     title = {Problemas de aproximaci\'on en espacios modulares de sucesiones dobles.},
     journal = {Publicacions matem\`atiques},
     pages = {259-268},
     year = {1990},
     volume = {34},
     number = {2},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/PM_1990_1990_1_a20/}
}