@article{UMJ_2018_4_2_a10,
     author = {Hanan Shabana},
     title = {$D_2$-synchronization in nondeterministic automata},
     journal = {Ural mathematical journal},
     pages = {99--110},
     publisher = {mathdoc},
     volume = {4},
     number = {2},
     year = {2018},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/UMJ_2018_4_2_a10/}
}