@article{IM2_2002_66_6_a3,
     author = {G. G. Laptev},
     title = {Absence of solutions of differential inequalities and systems of hyperbolic type in conic domains},
     journal = {Izvestiya. Mathematics},
     pages = {1147--1170},
     year = {2002},
     volume = {66},
     number = {6},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_2002_66_6_a3/}
}