@article{MZM_2020_108_3_a8,
     author = {I. G. Tsar'kov},
     title = {The {Geometry} of a {Singular} {Set} of {Hypersurfaces} and the {Eikonal} {Equation}},
     journal = {Matemati\v{c}eskie zametki},
     pages = {441--451},
     publisher = {mathdoc},
     volume = {108},
     number = {3},
     year = {2020},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_2020_108_3_a8/}
}