@article{TIMM_2008_14_3_a5,
     author = {V. I. Berdyshev},
     title = {Two methods of characterizing the visibility of a~moving point},
     journal = {Trudy Instituta matematiki i mehaniki},
     pages = {69--81},
     publisher = {mathdoc},
     volume = {14},
     number = {3},
     year = {2008},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TIMM_2008_14_3_a5/}
}