@article{SM_1987_56_1_a10,
     author = {N. G. Ananov and Yu. D. Burago and V. A. Zalgaller},
     title = {Three-dimensional manifolds of nonnegative {Ricci} curvature, with boundary},
     journal = {Sbornik. Mathematics},
     pages = {163--186},
     year = {1987},
     volume = {56},
     number = {1},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1987_56_1_a10/}
}