@article{10_4171_dm_233,
     author = {Pierre Guillot},
     title = {Geometric methods for cohomological invariants},
     journal = {Documenta mathematica},
     pages = {521--545},
     year = {2007},
     volume = {12},
     doi = {10.4171/dm/233},
     url = {http://geodesic.mathdoc.fr/articles/10.4171/dm/233/}
}