1. There is a good discussion in Treverton, ibid., chapters 5–6
2. Treverton , Covert Action, p. 11
3. Joel Rudinow makes a similar point in “Manipulation,”Ethics, Vol. 88 (1978) p. 347
4. Barrett Michael J. , “Honorable Espionage II,”Journal of Defense and Diplomacy, Vol. 2, No. 3 (March 1984) p. 14. (Barrett was assistant general counsel of the CIA at the time this article was written.)