@article{SM_1995_80_1_a8,
     author = {\`E. B. Vinberg},
     title = {The smallest field of definition of a~subgroup of the~group $\mathrm{PSL}_2$},
     journal = {Sbornik. Mathematics},
     pages = {179--190},
     publisher = {mathdoc},
     volume = {80},
     number = {1},
     year = {1995},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1995_80_1_a8/}
}