@article{VMUMM_1989_5_a6,
     author = {V. P. Kostov and B. Z. Shapiro},
     title = {The flags in $\mathbf{R}^3$, transversal to a given set of flags, form an $M$-manifold},
     journal = {Vestnik Moskovskogo universiteta. Matematika, mehanika},
     pages = {26--30},
     publisher = {mathdoc},
     number = {5},
     year = {1989},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VMUMM_1989_5_a6/}
}