@article{DE_1992_28_4_a6,
     author = {E. I. Nikol'skaya},
     title = {An estimate for the difference of partial sums of expansions of an absolutely continuous function in root functions corresponding to two one-dimensional {Schr\"odinger} operators with complex-valued potentials in the class $L_1$},
     journal = {Differencialʹnye uravneni\^a},
     pages = {598--612},
     publisher = {mathdoc},
     volume = {28},
     number = {4},
     year = {1992},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1992_28_4_a6/}
}