@article{GDZPPN002060132, title = {Primitivity in torsion free cohomology Hopf algebras}, journal = {Commentarii mathematici Helvetici}, volume = {46}, year = {1971}, pages = {13-43}, zbl = {0225.57023}, url = {http://dml.mathdoc.fr/item/GDZPPN002060132} }
Hubbuck, J.R. Primitivity in torsion free cohomology Hopf algebras. Commentarii mathematici Helvetici, Tome 46 (1971) pp. 13-43. http://gdmltest.u-ga.fr/item/GDZPPN002060132/