@article{MZM_1970_8_6_a4,
     author = {V. A. Liskovets},
     title = {The number of strongly connected directed graphs},
     journal = {Matemati\v{c}eskie zametki},
     pages = {721--732},
     publisher = {mathdoc},
     volume = {8},
     number = {6},
     year = {1970},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1970_8_6_a4/}
}