@article{PM_2002_2002_1_a23,
     author = {Duoandikoetxea, Javier},
     title = {Operadores direccionales y normas mixtas.},
     journal = {Publicacions matem\`atiques},
     pages = {39-56},
     publisher = {mathdoc},
     volume = {46},
     number = {Extra},
     year = {2002},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/PM_2002_2002_1_a23/}
}