This chart presents the authorities used in researching tax law. Subsequent pages of this guide will discuss these sources in more detail. Since 1996, the federal Freedom of Information Act, 5 USC Sec.552, has mandated that many sources of tax law must be made publicly available. The IRS accomplishes this through the IRS Electronic Reading Room. This guide will refer to that source frequently.
Source: Joni Larson & Dan Scheaffer, Federal Tax Research (2nd ed. 2011).