@article{AA_1989_1_5_a1,
     author = {S. V. Buyalo},
     title = {Collapsing manifolds of nonpositive {curvature.~I}},
     journal = {Algebra i analiz},
     pages = {74--94},
     publisher = {mathdoc},
     volume = {1},
     number = {5},
     year = {1989},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AA_1989_1_5_a1/}
}