Eigenvalues and Stacking Methods in Ergodic Theory Richard Turek Indiana University Mathematics Journal 1978 text pdf 10.1512/iumj.1978.27.27001 10.1512/iumj.1978.27.27001 en Indiana Univ. Math. J. 27 (1978) 1 - 8 state-of-the-art mathematics http://iumj.org/access/