@article{DM_1999_11_4_a6,
     author = {D. E. Efimov},
     title = {An estimate for the exponent of some sets of nonnegative matrices},
     journal = {Diskretnaya Matematika},
     pages = {79--88},
     year = {1999},
     volume = {11},
     number = {4},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DM_1999_11_4_a6/}
}