@article{MAN_1970__185_161944,
     author = {G. TSAGAS},
     title = {On the {Cohomology} {Ring} of a {Pinched} {Riemannian} {Manifold} of {Dimension} 4.},
     journal = {Mathematische Annalen},
     pages = {75--80},
     publisher = {mathdoc},
     volume = {185},
     year = {1970},
     zbl = {0181.24404},
     url = {http://geodesic.mathdoc.fr/item/MAN_1970__185_161944/}
}