A popular theory is that Benjamin Sisko created time in the 1990s by explaining it to the Prophets of the wormhole. Quark and Brunt made it part of their bestselling ebook/paperbook "Distilled Wisdom of the Prophets for Profits" which they sent 'back in time' out of mischief.
A theory I made up now is that The alicorn pony Princess Celestia wrote a parodical but educational book about science, and Discord sent it back.
In Fantastecha™, there are many strange loops and "plagiarism" is common and encouraged.