@article{DE_1989_25_7_a21,
     author = {E. V. Ferapontov},
     title = {Reciprocal transformations and their invariants},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1256--1265},
     publisher = {mathdoc},
     volume = {25},
     number = {7},
     year = {1989},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1989_25_7_a21/}
}