@article{PDM_2016_3_a2,
     author = {A. Yu. Zubov},
     title = {On the concept of a~$\varepsilon$-perfect cipher},
     journal = {Prikladna\^a diskretna\^a matematika},
     pages = {45--52},
     year = {2016},
     number = {3},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/PDM_2016_3_a2/}
}