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2. H. Cartan, Cohomologie des groupes, suite spectrale, faisceaux, Seminaire H. Cartan, 1950-1951 (mimeographed notes).
3. Princeton Landmarks in Mathematics;Cartan, Henri,1999
4. On the impossibility of fibring certain manifolds by a compact fibre;Conner, P. E.;Michigan Math. J.,1957
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