The Open Library Blog: “Open Library now lets you search inside the text contents of over 4M books. Many book websites, like Amazon and Goodreads, give you the ability to search for books by title and author, but they don’t make it easy to find books based on their contents. This type of searching is called “Full-Text Search”…When you search across 40M documents, it can be a challenge to find the one you’re looking for. One feature which Open Library has been missing is a way to limit Internet Archive’s full-text search to only include results from books on Open Library. So for the last two years, Open Library has patiently waited to take full advantage of full-text search for its users. Earlier this week, Giovanni Damiola (@giovannidamiola) released an improvement to our full-text search engine which lets us get around this historical limitation — and so we jumped on this opportunity to improve our search on openlibrary.org! With the help of Razzi Abuissa, Open Library volunteer, and Mek, Open Library’s project lead, you can now search inside more than 4M Open Library books…”

See also the Advanced Search feature – https://openlibrary.org/advancedsearch