@article{DE_1989_25_3_a13,
     author = {M. Utepbergenov},
     title = {A method for studying regular singularities of partial differential equations},
     journal = {Differencialʹnye uravneni\^a},
     pages = {499--505},
     publisher = {mathdoc},
     volume = {25},
     number = {3},
     year = {1989},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1989_25_3_a13/}
}