You can search for just about anything. You have to see this to believe it. Searchable index to roughly 2,400 journals in different fields.
Many sources provide full text or pdf downloads of articles.
Another amazing reference database. Presidential Libraries Web . Starting with Hoover, a separate library has been established for each President. These libraries are the primary archives for each administration, and contain millions of pages of documents. The libraries, run by the National Archives and Records Administration, are starting to go on-line.