The U.S. Government Accountability Office (GAO) is an independent, nonpartisan agency that investigates how the federal government spends taxpayer dollars. The GAO produces reports (often called "blue books"), testimonies, legal decisions and opinions and makes them available to the public on its website. Users can search for GAO reports or browse reports by date, topic or government agency.
You can also locate GAO reports on FDSys (administered by the Government Printing Office). Select the "Advanced Search option and then "GAO Reports and GAO Comptroller General Decisions."