@article{DE_1976_12_3_a0,
     author = {N. P. Erugin},
     title = {Theory of moving singular points of second order {equations.~I}},
     journal = {Differencialʹnye uravneni\^a},
     pages = {387--416},
     publisher = {mathdoc},
     volume = {12},
     number = {3},
     year = {1976},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1976_12_3_a0/}
}