@article{SM_1989_63_2_a2,
     author = {S. M. L'vovskii},
     title = {On the extension of varieties defined by quadratic equations},
     journal = {Sbornik. Mathematics},
     pages = {305--317},
     publisher = {mathdoc},
     volume = {63},
     number = {2},
     year = {1989},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1989_63_2_a2/}
}