@article{CRMATH_2007__344_10_621_0,
     author = {Nicolas, Jean-Philippe},
     title = {On {Lars} {H\"ormander's} remark on the characteristic {Cauchy} problem},
     journal = {Comptes Rendus. Math\'ematique},
     pages = {621--626},
     publisher = {Elsevier},
     volume = {344},
     number = {10},
     year = {2007},
     doi = {10.1016/j.crma.2007.03.010},
     language = {en},
     url = {http://www.numdam.org/articles/10.1016/j.crma.2007.03.010/}
}