Levinson, Paul. Loose Ends
Series note: A series of similarly themed short stories: "Loose Ends", "Little Differences", and "Late Lessons".

Levinson, Paul. "Loose Ends"
Summary: A time traveler on a mission to prevent the Challenger disaster somehow ends up in 1963 instead.
Series note: First of the Loose Ends stories.
Comments: Actual allohistorical content is almost nil, consisting of just a few sentences near the story's end.
Published: In Analog, May 1997.
Original in: English.
Translation: Italian by Enzo Verrengia as "Niente fuori posto", in Strani universi (ed. Piergiorgio Nicolazzini), Nord 1998 (884291035X).

Levinson, Paul. "Little Differences"
Summary: Stuck in 1968, the time traveler tries several times over the years to change history, but accomplishes nothing.
Series note: Second of the Loose Ends stories.
Published: In Analog, June 1998.

Levinson, Paul. "Late Lessons"
Series note: Third of the Loose Ends stories.
Published: In Analog , October 1999.