@article{PDMA_2019_12_a54,
     author = {I. V. Kolbasina and K. V. Safonov},
     title = {A solvability condition for arbitrary formal grammars},
     journal = {Prikladnaya Diskretnaya Matematika. Supplement},
     pages = {196--198},
     publisher = {mathdoc},
     number = {12},
     year = {2019},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/PDMA_2019_12_a54/}
}