Don't have access to ProQuest or Hein? Or need a "quick and dirty" legislative history? Look to the U.S. Code Congressional and Administrative News (a.k.a. USCAAN) for a concise legislative history. Look up the public law number in the LH volume of the appropriate year.
Print Sources
•Barton's Federal Tax Laws Correlated (1913-1954). KF6335 .A3 1968.
•Seidman's Legislative History of Federal Income & Excess Profits Tax Laws 1953-1939. KF6369 .S448 2003. Also available online.
•Seidman's Legislative History of Federal Income & Excess Profits Tax Laws 1938-1861 . KF6369 .S45 2003. Also available online.
•West's Internal Revenue Acts: Text & Legislative History (annual, as needed). KF6265.99 U54.
Online Sources:
For compiled legislative histories, use ProQuest Legislative Insight.
For a comprehensive search of congressional documents, use ProQuest Congressional.
You can find older editions of the United States Code, CFR, and Federal Register on HeinOnline.
Westlaw Edge now has an link which allows users to compare versions of statutes or regulations over a period of time. Start by pulling up the statute or regulation and then look for the Compare Versions link in the top right quadrant, near the delivery icons.