@article{CMFD_2013_51_a1,
     author = {M. V. Zenkina},
     title = {An invariant of knots in thickened surfaces},
     journal = {Contemporary Mathematics. Fundamental Directions},
     pages = {21--32},
     year = {2013},
     volume = {51},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/CMFD_2013_51_a1/}
}