Here are 2 recent items analyzing Hathitrust and Google books for their efficacy in giving access to Federal government documents. The first is an article by Laura Sare (Texas A&M) and compares Hathitrust with Google Books. The second is a presentation by Brian Vetruba (Washington U in St Louis) at “Leveraging Your Strengths: Regional Government Documents Conference” at the Federal Reserve Bank St. Louis on May 4, 2012.
A Comparison of HathiTrust and Google Books Using Federal Publications. Laura Sare. Practical Academic Librarianship: The International Journal of the SLA Academic Division. 2(1) 2012 p. 1-25. (attached below. Fair use claim)