Federal tax laws come from four sources:
The U.S. Department of Treasury is the executive department responsible for implementing tax laws.
The Internal Revenue Service (IRS), a bureau within the Treasury Department, issues documents for interpreting the IRC and enforcing tax laws--regulations to letters commenting on specific transactions. Many of these documents are called regulations.
What Newman databases offer these sources?
The major tax codifications are the IRC of 1939, 1954, 1986 and 2018.
Annual editions have been published.