@article{DM_2013_25_4_a2,
     author = {A. A. Letunovskii},
     title = {Cycle indices of an automaton},
     journal = {Diskretnaya Matematika},
     pages = {24--29},
     year = {2013},
     volume = {25},
     number = {4},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DM_2013_25_4_a2/}
}