Part 1. Introduction and preliminaries Part 2. Reducing the proof of the main results to the construction of $n$-regular and $n$-semiregular $\mathcal {N}_n$-covers Part 3. Constructing $n$-semiregular and $n$-regular $\mathcal {N}_n$-covers
Notes
"May 2013, Volume 223, Number 1048 (second of 5 numbers)."
Bibliography
Includes bibliographical references (pages 89-90) and index