@article{IVM_2010_1_a5,
     author = {P. V. Martyugin},
     title = {A lower bound for the length of the shortest carefully synchronizing words},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {59--68},
     publisher = {mathdoc},
     number = {1},
     year = {2010},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_2010_1_a5/}
}