@article{FPM_2000_6_3_a8,
     author = {T. V. Dubrovina and N. I. Dubrovin},
     title = {Roots in the universal covering group of the unimodular $2\times2$-matrix group},
     journal = {Fundamentalʹna\^a i prikladna\^a matematika},
     pages = {757--776},
     publisher = {mathdoc},
     volume = {6},
     number = {3},
     year = {2000},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/FPM_2000_6_3_a8/}
}