@article{SM_2006_197_6_a4,
     author = {V. M. Levchuk and O. A. Starikova},
     title = {Quadratic forms of projective spaces over rings},
     journal = {Sbornik. Mathematics},
     pages = {887--899},
     publisher = {mathdoc},
     volume = {197},
     number = {6},
     year = {2006},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_2006_197_6_a4/}
}