@article{MZM_2003_74_5_a11,
     author = {S. E. Stepanov and I. G. Shandra},
     title = {Seven {Classes} of {Harmonic} {Diffeomorphisms}},
     journal = {Matemati\v{c}eskie zametki},
     pages = {752--761},
     year = {2003},
     volume = {74},
     number = {5},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_2003_74_5_a11/}
}