Combine intitle:index.of with epub and your book title.
Commercial platforms only host books that are profitable enough to justify licensing costs. If a book falls out of print or exists in a legal gray area of orphan works, corporations delete it. Open indexes are frequently maintained by digital archivists, academics, and hobbyists who preserve rare, academic, or obscure texts that are otherwise unavailable to the public. 4. Risks, Safety, and Digital Hygiene index of epub books better
Even more critically, relying exclusively on search eliminates the value of synonyms and related terms that human indexers provide. A good index considers these relationships, making it much more likely to find everything relevant to a topic than a simple text search. Combine intitle:index