@article{MZM_2022_112_4_a1,
     author = {A. I. Aptekarev and Yu. G. Rykov},
     title = {Emergence of a {Hierarchy} of {Singularities} in {Zero-Pressure} {Media.} {Two-Dimensional} {Case}},
     journal = {Matemati\v{c}eskie zametki},
     pages = {486--499},
     publisher = {mathdoc},
     volume = {112},
     number = {4},
     year = {2022},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_2022_112_4_a1/}
}