@article{MZM_1985_38_2_a13,
     author = {P. Ya. Grushko},
     title = {Contractibility of geometric structures},
     journal = {Matemati\v{c}eskie zametki},
     pages = {293--301},
     publisher = {mathdoc},
     volume = {38},
     number = {2},
     year = {1985},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1985_38_2_a13/}
}