@article{IM2_1991_36_1_a9,
     author = {B. Z. Shapiro},
     title = {Spaces of linear differential equatios, and flag manifolds},
     journal = {Izvestiya. Mathematics },
     pages = {183--197},
     publisher = {mathdoc},
     volume = {36},
     number = {1},
     year = {1991},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1991_36_1_a9/}
}