Online sources of gray literature, which includes data, reports, lab notes, ephemera with informational value, unpublished manuscripts, pre-prints, and other information sources that are valuable to scholars but not published in the traditional sense.
This specialized search engine searches Thomas, U.S. House, U.S. Senate, Congressional Budget Office (CBO), Government Accountabilty Office (GAO), Office of Management and Budget (OMB), the Washington Post, etc. From the University of California Berkeley Library.