While there are other sources of government documents online, the GPO is often the best place to start. FDsys. Many of the documents they provide are in both, but some are still only available on GPO Access.
GPO Access documents have their own search tools. FDsys, on the other hand, combines them all into one powerful search engine. You can browse the documents by collection, congressional committee or date. Or use the Advanced Search, which allows you to specify specific documents or search all of them at once.
Some of the GPO's offerings include:
We have a wealth of books covering the U.S. government, its history, and current issues. Possible searches could include:
If your first search brings up too many irrelevant items, try using the Refine by Topic suggestions in the box on the left of the search results screen.
Here are some reference books that may be useful: