@article{TRSPY_2002_239_a12,
     author = {M. D. Kovalev},
     title = {Quadratic and {Rigidity} {Mappings}},
     journal = {Informatics and Automation},
     pages = {195--214},
     publisher = {mathdoc},
     volume = {239},
     year = {2002},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TRSPY_2002_239_a12/}
}