@article{PDMA_2012_5_a35,
     author = {D. N. Kolegov},
     title = {Hierarchical role-based access control},
     journal = {Prikladnaya Diskretnaya Matematika. Supplement},
     pages = {69--71},
     publisher = {mathdoc},
     number = {5},
     year = {2012},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/PDMA_2012_5_a35/}
}