I believe this one speaks for itself. It was found 19 years ago inside a book checked out from the Hampton Public Library. The book was Watership Down and the page was 10.
Quite often employees of Dedonde Inc. or even Doom Riders would attempt to infiltrate weekly Resistance meetings. They did not dare enter, but would watch from nearby and document anything they could. This was typically reported back to Dedonde Headquarters via paper. Occasionally, the spy would be discovered during the meeting and either chased or murdered. I believe this note was written by a Dedonde employee who was chased but not caught. He most likely hid the paper in the nearest public library and then promptly time jumped. We might never know.