@article{10_1007_s10587_015_0175_4,
     author = {S{\l}anina, Piotr},
     title = {On some free semigroups, generated by matrices},
     journal = {Czechoslovak Mathematical Journal},
     pages = {289--299},
     publisher = {mathdoc},
     volume = {65},
     number = {2},
     year = {2015},
     doi = {10.1007/s10587-015-0175-4},
     mrnumber = {3360426},
     zbl = {06486946},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.1007/s10587-015-0175-4/}
}