David Wilkins. "The Enemy And His Tactics". 5th Battalion, Royal Australian Regiment Association. Archived from the original on 8 March 2020. Retrieved 12 May 2014.
Frazier 1978, p. 119. AID Director John Hannah stated in a letter dated May 9, 1973, that: "Plan F-6 is an acceleration of the Phuong Hoang (Phoenix) operation which the GVN directed in view of the North Vietnamese invasion of 1972." Frazier, H. (1978). Uncloaking the CIA. Free Press. ISBN978-0-02-915360-4.
David Wilkins. "The Enemy And His Tactics". 5th Battalion, Royal Australian Regiment Association. Archived from the original on 8 March 2020. Retrieved 12 May 2014.