@article{RMI_1993_1993_1_a9,
     author = {Varopoulos, Nicholas Th.},
     title = {Conmutadores de semigrupos bajo diferencias {(II).}},
     journal = {Revista matem\'atica iberoamericana},
     pages = {1-50},
     year = {1993},
     volume = {9},
     number = {1},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/RMI_1993_1993_1_a9/}
}