@article{TDM_2004_8_a10,
     author = {Yu. I. Maksimov},
     title = {Some results for the {Markov} chain lumping problem},
     journal = {Trudy po diskretnoj matematike},
     pages = {148--154},
     publisher = {mathdoc},
     volume = {8},
     year = {2004},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TDM_2004_8_a10/}
}