@article{TMF_2009_159_3_a12,
     author = {D. J. Kaup},
     title = {Integrable systems and squared eigenfunctions},
     journal = {Teoreti\v{c}eska\^a i matemati\v{c}eska\^a fizika},
     pages = {459--474},
     publisher = {mathdoc},
     volume = {159},
     number = {3},
     year = {2009},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TMF_2009_159_3_a12/}
}