In an undertaking of this sort a researcher-author becomes indebted to many people for help of one kind or another. I should like to acknowledge my indebtedness and offer my sincere thanks to the following persons.
For their help in connection with my research, I thank Alton K. Cavin, Robert R. Wilson, J. B. Lowenhaupt, John Rankin, H. Roy McBroom, N. 0. Frederick, A. Dewey Acuff, Jack Hendricks, J. Rogers Pearcy, John M. Meier, Lowell G. Hammons, Harry McAndrews, Gary Bennethum, William Moffat, Darius W. Gaskins, Collis P. Chandler, Bob Burch, and Milton Lipton.
My thanks go also to those who read earlier versions of the manuscript and made helpful comments: James W. McKie, Herbert H. Liebhafsky, Hermann Enzer, William A. Vogely, Robert Adams, Robert J. Kalter, Wallace E. Tyner, Patrick H. Goehan, Hans H. Landsberg, John J. Schanz, Walter J. Mead, Carl C. Traywick, Vincent J. Geraci, and George Heitmann.
If, despite all this help, errors remain in the manuscript, I alone am responsible for them.
Finally, I am most grateful to Resources for the Future for their generous grant which made this work possible.
Austin, Texas Stephen L. McDonald