@article{MZM_1976_20_3_a7,
     author = {B. A. Ivanov},
     title = {Exceptional directions for a~convex body},
     journal = {Matemati\v{c}eskie zametki},
     pages = {365--371},
     publisher = {mathdoc},
     volume = {20},
     number = {3},
     year = {1976},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1976_20_3_a7/}
}