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3. F. T. Farrell, The obstruction to fibering a manifold over a circle, Proc. I.C.M. Nice (1970), vol. 2, 69–72.
4. B. Friberg, A topological proof of a theorem of Kneser, Proc. Amer. Math. Soc.
5. A Haefliger, Lissage des immersions II, bluemimeo, Geneva 1697 ±.