@article{AA_2021_33_1_a3,
     author = {S. V. Ivanov},
     title = {Distance difference functions on nonconvex boundaries of {Riemannian} manifolds},
     journal = {Algebra i analiz},
     pages = {81--92},
     publisher = {mathdoc},
     volume = {33},
     number = {1},
     year = {2021},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AA_2021_33_1_a3/}
}