@article{10_4171_dm_2,
     author = {Nikita A. Karpenko},
     title = {Order of torsion in {CH⁴} of quadrics},
     journal = {Documenta mathematica},
     pages = {57--65},
     year = {1996},
     volume = {1},
     doi = {10.4171/dm/2},
     url = {http://geodesic.mathdoc.fr/articles/10.4171/dm/2/}
}