@article{MZM_2005_77_6_a9,
     author = {S. P. Khekalo},
     title = {Stepwise {Gauge} {Equivalence} of {Differential} {Operators}},
     journal = {Matemati\v{c}eskie zametki},
     pages = {917--929},
     publisher = {mathdoc},
     volume = {77},
     number = {6},
     year = {2005},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_2005_77_6_a9/}
}