@article{VMUMM_1990_5_a13,
     author = {E. V. Moiseev},
     title = {Contractability of a superextension},
     journal = {Vestnik Moskovskogo universiteta. Matematika, mehanika},
     pages = {64--66},
     year = {1990},
     number = {5},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VMUMM_1990_5_a13/}
}