(Mitroff & Turoff, 2002, p. 27)

Mitroff, I. I., & Turoff, M. (2002). Philosophical and Methodological Foundations of Delphi. In H. A. Linstone & M. Turoff (Eds.), The Delphi method: Techniques and applications (pp. 17–34). Addison-Wesley Pub. Co., Advanced Book Program.