@article{DAN_1969_184_2_a10,
     author = {V. A. Toponogov},
     title = {Extremal theorems for {Riemannian} spaces with curvature bounded from above},
     journal = {Doklady Akademii Nauk},
     pages = {300--302},
     publisher = {mathdoc},
     volume = {184},
     number = {2},
     year = {1969},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1969_184_2_a10/}
}