chapter has its own bibliography; references within the text are by name of author.
The present form of the book owes a great deal to the questions and remarks of the many students who have taken the course. I wish to thank in particular my former Ph.D. students Judith M. Elkins, Maynard D. Thompson, and Gilbert G. Walter who commented on early versions of some of the material; remarks by certain anonymous referees have also been very helpful. It is a pleasure to acknowledge the assistance by members of the mathematics office staffs, both at the University of Wisconsin and the University of California, San Diego, who helped prepare successive approximations to the final manuscript in the form of lecture notes. Thanks are due also to the staff of Academic Press. Last but not least, I wish to mention the special support of my wife Jopie, who suffered it all (if not altogether in silence).
La Jolla, Californi Jacob Korevaar
December, 1967