@article{DAN_1989_307_4_a4,
     author = {I. M. Gel'fand and G. L. Rybnikov},
     title = {Algebraic and topological invariants of oriented matroids},
     journal = {Doklady Akademii Nauk},
     pages = {791--795},
     publisher = {mathdoc},
     volume = {307},
     number = {4},
     year = {1989},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1989_307_4_a4/}
}