@article{MM_2000_12_2_a8,
     author = {I. P. Denisova and A. A. Zubrilo},
     title = {Mathematical model of concave gravitational lens},
     journal = {Matemati\v{c}eskoe modelirovanie},
     pages = {68--74},
     publisher = {mathdoc},
     volume = {12},
     number = {2},
     year = {2000},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MM_2000_12_2_a8/}
}