@article{TIMB_2017_25_2_a4,
     author = {E. K. Makarov and I. V. Marchenko},
     title = {On upward mobility of the highest exponent of a linear differential system under perturbations of the coefficients from the simplest classes with degeneracies},
     journal = {Trudy Instituta matematiki},
     pages = {50--59},
     publisher = {mathdoc},
     volume = {25},
     number = {2},
     year = {2017},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TIMB_2017_25_2_a4/}
}