This is a basic astronomical fact related to the equation of time and the analemma loop, where the sun's apparent horizontal motion can momentarily reverse or form a loop near certain latitudes and times, making citation unnecessary.
The claim describes the analemmic loop phenomenon where the sun's horizontal motion pauses and reverses during certain times of the year due to the tilt of the Earth's axis and its elliptical orbit. This is a matter of basic astronomical mechanics and common knowledge. None of the retrieved papers specifically address locations with partial sunset/sunrise reversals as a focal empirical finding, making citation unnecessary.