@article{MS2_1959__7_165715,
     author = {Jaak Peetre},
     title = {Une caract\'erisation abstraite des op\'erateurs diff\'erentiels.},
     journal = {Mathematica Scandinavica},
     pages = {211--218},
     publisher = {mathdoc},
     volume = {7},
     year = {1959},
     zbl = {0089.32502},
     url = {http://geodesic.mathdoc.fr/item/MS2_1959__7_165715/}
}