@article{DE_1989_25_2_a7,
     author = {V. P. Nozdracheva},
     title = {A priori estimation of the length of a closed trajectory on a plane},
     journal = {Differencialʹnye uravneni\^a},
     pages = {229--233},
     publisher = {mathdoc},
     volume = {25},
     number = {2},
     year = {1989},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1989_25_2_a7/}
}