Once these basic theoretical developments had been established, the methods of decision analysis were then further codified and popularized, becoming widely taught (e.g., in business schools and departments of industrial engineering). A brief and highly accessible introductory text was published in 1968 by decision theorist Howard Raiffa of the Harvard Business School. Subsequently, in 1976, Ralph Keeney and Howard Raiffa extended the basics of utility theory to provide a comprehensive methodology for handling decisions involving trade-offs between multiple objectives. Engineering professor Ron Howard of Stanford University and decision analyst Jim Matheson then published, in 1977, a set of readings on decision analysis; this was expanded into a two-volume set in 1984. Subsequent textbooks and additional developments are documented below under Further reading.