@article{10_1090_S0894_0347_02_00418_6,
     author = {Belegradek, Igor and Kapovitch, Vitali},
     title = {Obstructions to nonnegative curvature and rational homotopy theory},
     journal = {Journal of the American Mathematical Society},
     pages = {259--284},
     publisher = {mathdoc},
     volume = {16},
     number = {2},
     year = {2003},
     doi = {10.1090/S0894-0347-02-00418-6},
     url = {http://geodesic.mathdoc.fr/articles/10.1090/S0894-0347-02-00418-6/}
}