@article{FPM_2013_18_4_a6,
     author = {V. O. Manturov and D. A. Fedoseev},
     title = {Invariants of homotopy classes of curves and graphs on $2$-surfaces},
     journal = {Fundamentalʹna\^a i prikladna\^a matematika},
     pages = {89--105},
     publisher = {mathdoc},
     volume = {18},
     number = {4},
     year = {2013},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/FPM_2013_18_4_a6/}
}