@article{IM2_1973_7_6_a4,
     author = {A. V. Kochergin},
     title = {Time changes in flows and mixing},
     journal = {Izvestiya. Mathematics},
     pages = {1273--1294},
     year = {1973},
     volume = {7},
     number = {6},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1973_7_6_a4/}
}