@article{MZM_2007_82_3_a10,
     author = {R. M. Trigub},
     title = {Comparison of {Linear} {Differential} {Operators}},
     journal = {Matemati\v{c}eskie zametki},
     pages = {426--440},
     publisher = {mathdoc},
     volume = {82},
     number = {3},
     year = {2007},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_2007_82_3_a10/}
}