@article{DAN_1992_323_1_a0,
     author = {V. A. Baltag and N. I. Vulpe},
     title = {The number and multiplicity of singular points of a quadratic},
     journal = {Doklady Akademii Nauk},
     pages = {9--12},
     publisher = {mathdoc},
     volume = {323},
     number = {1},
     year = {1992},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1992_323_1_a0/}
}