@article{PDM_2019_1_a7,
     author = {V. M. Fomichev},
     title = {On improved universal estimation of exponents of~digraphs},
     journal = {Prikladna\^a diskretna\^a matematika},
     pages = {115--123},
     publisher = {mathdoc},
     number = {1},
     year = {2019},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/PDM_2019_1_a7/}
}