From a HathiTrust Blog Post:
This sentence appeared not in the style section of the Atlanta newspaper but at the start of an interoffice memo between Internal Revenue Service offices. The full memo and the backstory can be found in the six millionth openly available item deposited in HathiTrust, digitized by the University of California, Riverside.
There are many reasons HathiTrust’s six million open volumes are open: some are in the public domain in the United States, some worldwide, and some have been licensed for public view by the rightsholder, usually with a Creative Commons license. Over 1 million of these are publications of which by statute are not afforded protection by copyright in the US.
See Also: Visualizations of HathiTrust by
See Also: HathiTrust Update, January 31, 2018