Not OP. Have you perused these references from the Wikipedia page for OODA loop? The reference to a “supposed slide set” sounds interesting; perhaps that is what you’re alluding to regarding source material being hard to find?
Boyd, John R. (3 September 1976). Destruction and Creation (PDF). U.S. Army Command and General Staff College.
Boyd, John R. (3 September 1976). Destruction and Creation (PDF). U.S. Army Command and General Staff College.
https://upload.wikimedia.org/wikipedia/commons/a/a6/Destruct...
Boyd, John, R. (28 June 1995). "The Essence of Winning and Losing". danford.net. A supposed five-slide set by Boyd.
https://danford.net/boyd/essence.htm
https://en.wikipedia.org/wiki/OODA_loop