"This is a revised version of a paper presented at the conference, Productivity Measurement in Regulated Industries, University of Wisconsin-Madison, April 30--May 1, 1979. It will be published in Productivity Measurement in Regulated Industries, T. G. Cowing and R. E. Stevenson, editors (Academic Press, 1980)."
"September 1979."
Includes bibliographical references (pages 56-58).