@article{PDM_2011_13_a29,
     author = {K. V. Safonov and D. A. Kalugin-Balashov},
     title = {About phrase-structure grammar property},
     journal = {Prikladna\^a diskretna\^a matematika},
     pages = {60--61},
     publisher = {mathdoc},
     number = {13},
     year = {2011},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/PDM_2011_13_a29/}
}