The Obstruction to Fibering a Manifold over a Circle F. Farrell Indiana University Mathematics Journal 1972 text pdf 10.1512/iumj.1972.21.21024 10.1512/iumj.1972.21.21024 en Indiana Univ. Math. J. 21 (1972) 315 - 346 state-of-the-art mathematics http://iumj.org/access/