@article{SM_1969_8_3_a2,
     author = {I. S. Kats},
     title = {Compatibility of the coefficients of a~generalized second order linear differential equation},
     journal = {Sbornik. Mathematics},
     pages = {345--356},
     publisher = {mathdoc},
     volume = {8},
     number = {3},
     year = {1969},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1969_8_3_a2/}
}