@article{INTA_1990_28_a2,
     author = {S. A. Vakhrameev},
     title = {Hilbert manifolds with angles of finite codimension, and optimal control theory},
     journal = {Itogi Nauki i Tekhniki. Seriya Algebra. Geometriya. Topologiya},
     pages = {96--171},
     year = {1990},
     volume = {28},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/INTA_1990_28_a2/}
}