@article{UZKU_2018_160_4_a12,
     author = {A. V. Kazantsev},
     title = {The {Gakhov} barriers and extremals for the level lines},
     journal = {U\v{c}\"enye zapiski Kazanskogo universiteta. Seri\^a Fiziko-matemati\v{c}eskie nauki},
     pages = {750--761},
     publisher = {mathdoc},
     volume = {160},
     number = {4},
     year = {2018},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/UZKU_2018_160_4_a12/}
}