@article{FPM_2015_20_2_a3,
     author = {V. Dragovi\'c and M. Radnovi\'c},
     title = {Topological invariants for elliptical billiards and geodesics on ellipsoids in the {Minkowski} space},
     journal = {Fundamentalʹna\^a i prikladna\^a matematika},
     pages = {51--64},
     publisher = {mathdoc},
     volume = {20},
     number = {2},
     year = {2015},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/FPM_2015_20_2_a3/}
}