@article{PM_1992_1992_1_a13,
     author = {Romero Ruiz del Portal, Francisco},
     title = {Grado generalizado en espacios normados.},
     journal = {Publicacions matem\`atiques},
     pages = {157-166},
     publisher = {mathdoc},
     volume = {36},
     number = {1},
     year = {1992},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/PM_1992_1992_1_a13/}
}