Modifications and Cobounding manifolds, III. Andrew Wallace Indiana University Mathematics Journal 1962 text pdf 10.1512/iumj.1962.11.11056 10.1512/iumj.1962.11.11056 en Indiana Univ. Math. J. 11 (1962) 979 - 990 state-of-the-art mathematics http://iumj.org/access/