@article{SM_1967_2_2_a0,
     author = {M. S. Agranovich},
     title = {On the theory of boundary problems for symmetrizable systems of first order},
     journal = {Sbornik. Mathematics},
     pages = {143--171},
     publisher = {mathdoc},
     volume = {2},
     number = {2},
     year = {1967},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1967_2_2_a0/}
}