If you’ve searched Summon recently, then you may well have stumbled upon one of the 2.2 million public-domain books that are now available by HathiTrust, an international community of libraries committed to the long-term preservation of the cultural record. With a burden of that magnitude, it’s no wonder they’ve named themselves after an elephant known for its long-term memory.

Here’s how it works: when you search in Summon, you will see links to books digitized by libraries around the world. By default, only public domain works (books published before 1923 along with some government publications) will show up in your Summon results, like Mrs. McPiggs’ of the Very Old Scratch: A half grown novel written by Frank C. Voorhies in Boston in 1903 or Sustainability of Maine’s groundfish industry : field hearing before the Subcommittee on Oceans, Atmosphere, Fisheries, and Coast Guard of the Committee on Commerce, Science, and Transportation, from 2008.

Copyrighted titles (those published after 1923) or orphan titles with unknown copyright, will only appear if you select the “Add results beyond your library’s collection” option in the left-hand side of the screen:

Now, Summon will include citations for millions of copyrighted titles that match your search. Look for the note “Citation Online”  and a direct link to HathiTrust. While these copyrighted works won’t likely be available in full-text, Inter Library Loan or the New England Library Consortium (NExpress) might be able to get that book in your hands.