@article{DM_1993_5_4_a4,
     author = {L. P. Lisovik},
     title = {Inclusion and ambiguity problems for regular events in semigroups},
     journal = {Diskretnaya Matematika},
     pages = {54--74},
     publisher = {mathdoc},
     volume = {5},
     number = {4},
     year = {1993},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DM_1993_5_4_a4/}
}