@article{TIMM_2013_19_2_a7,
     author = {V. I. Berdyshev},
     title = {Differentiation of the concealment function in the case of a~convex occluding set},
     journal = {Trudy Instituta matematiki i mehaniki},
     pages = {79--84},
     year = {2013},
     volume = {19},
     number = {2},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TIMM_2013_19_2_a7/}
}