Yes, from the linked paper: "Books3 is a dataset of books derived from a copy of the contents of the Bibliotik private tracker made available by Shawn Presser

Yes, from the linked paper: "Books3 is a dataset of books derived from a copy of the contents of the Bibliotik private tracker made available by Shawn Presser (Presser, 2020). Bibliotik consists of a mix of fiction and nonfiction books and is almost an order of magnitude larger than our next largest book dataset (BookCorpus2). We included Bibliotik because books are invaluable for long-range context modeling research and coherent storytelling"