@article{CHFMJ_2019_4_4_a4,
     author = {R. K. Salimov and E. G. Ekomasov and A. M. Gumerov},
     title = {On nonstationary
},
     journal = {\v{C}el\^abinskij fiziko-matemati\v{c}eskij \v{z}urnal},
     pages = {419--426},
     publisher = {mathdoc},
     volume = {4},
     number = {4},
     year = {2019},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/CHFMJ_2019_4_4_a4/}
}