UFO Lecture (Summary):

“UFOs – A CHALLENGE TO OBSERVATION”

by Dr. James E. McDonald, 13 February 1969,
Washington, D.C. (Sign Historical Group)

The lecture was addressed to participants in the Symposium on Meteorological Observations and Instrumentation:

http://www.project1947.com/shg/articles/jmufocobs.html

NOTE: Project 1947 hosts the Sign Historical Group web page.

The late Dr. James E. McDonald,
U.S. Physicist & UFO Researcher
(wikimedia.org photo)