@article{IVM_2004_6_a1,
     author = {Yu. E. Boyarintsev and I. V. Orlova},
     title = {Block algebro-differential systems and their indices},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {6--13},
     publisher = {mathdoc},
     number = {6},
     year = {2004},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_2004_6_a1/}
}