@article{ZNSL_1999_261_a7,
     author = {S. E. Kozlov},
     title = {Stationary values of sectional curvature in {Grassmanian} manifolds of bivectors},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {102--118},
     publisher = {mathdoc},
     volume = {261},
     year = {1999},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1999_261_a7/}
}