@article{TMF_2012_173_2_a2,
     author = {A. B. Shabat and Z. S. El'kanova and A. B. Urusova},
     title = {Two-sided {Darboux} transformations},
     journal = {Teoreti\v{c}eska\^a i matemati\v{c}eska\^a fizika},
     pages = {207--218},
     year = {2012},
     volume = {173},
     number = {2},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TMF_2012_173_2_a2/}
}