unsigned_wastebin.md book found by the house of wastebin (real Minecraft username unknown) at 415 / 67 / -619 on the tilder server in the overworld.
The book was found in a chest with seemingly no other books around that location, even after looking.
Why these coordinates were written is unknown, as when going to 150, XXX, -25, nothing of note is seen there. If there was anything to be seen, it is now gone.
Nether:§0
§0150, Y, -25