@article{EXMATH_2007_2007_1_a1,
     author = {Matache, Valentin},
     title = {Distancias entre operadores de composici\'on.},
     journal = {Extracta mathematicae},
     pages = {19-33},
     publisher = {mathdoc},
     volume = {22},
     number = {1},
     year = {2007},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/EXMATH_2007_2007_1_a1/}
}