@article{RMI_2007_2007_1_a19,
     author = {Bournaveas, N. and  Guti\'errez, S.},
     title = {On the regularity of averages over spheres for kinetic transport equations in hyperbolic {Sobolev} spaces.},
     journal = {Revista matem\'atica iberoamericana},
     pages = {481-512},
     publisher = {mathdoc},
     volume = {23},
     number = {2},
     year = {2007},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/RMI_2007_2007_1_a19/}
}