@article{SM_1983_44_3_a1,
     author = {Yu. N. Drozhzhinov},
     title = {Passive linear systems of partial differential equations},
     journal = {Sbornik. Mathematics},
     pages = {269--278},
     publisher = {mathdoc},
     volume = {44},
     number = {3},
     year = {1983},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1983_44_3_a1/}
}