@article{PDM_2011_1_a4,
     author = {E. A. Tolyupa},
     title = {Some proxy signature protocols},
     journal = {Prikladna\^a diskretna\^a matematika},
     pages = {70--77},
     publisher = {mathdoc},
     number = {1},
     year = {2011},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/PDM_2011_1_a4/}
}