From the files of Project Blue Book, this July 19, 1949 UFO incident seems to have been a pretty straightforward airplane that was misidentified.
For more incidents around the world, visit the following links.
UFO Database
Mutual UFO Network
National UFO Reporting Center
From the files of Project Blue Book, this Strange Columbus March 13, 1952 UFO event was ultimately concluded to have been a B-45 plane.
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UFO Database
From the files of Project Blue Book, the February 26, 1954 UFO event was more extensively detailed in its investigation than others, with the conclusion being that it was a common airplane.
To view more incidents from around the world, go here.
UFO Database