UFO Book Chapter: “THE UFO EVIDENCE: SECTION VIII: SPECIAL EVIDENCE”

1964 
(National Investigations Committee on Aerial Phenomena,

Washington, D.C.) 

Source: NICAP.org

Quote from the chapter:

“There are three basic types of UFO reports:

(1) UFOs detected by the unaided human senses.

(2) UFOs detected by instruments, but not by human senses.

(3) UFOs detected by the human senses, substantiated by instruments.”

http://www.nicap.org/ufoe/section_8.htm

“Radar Cases”

(date range: summer 1948-29 January 1962) (most of these UFO incidents were witnessed by U.S. Air Force pilots/personnel):

http://www.nicap.org/ufoe/ufoe76.htm

(abovetopsecret.com image)