After the bill is passed by Congress, the President must sign the bill into law. Sometimes he will send a presidential message with the bill which may help clarify intent, especially for bills proposed by the executive branch. These appear in the Weekly Compilation of Presidential Documents or the Public Papers of the Presidents of the United States.
Bluebook Citation T1 p. 244
Other Presidential Papers: cite to the Public Papers of the Presidents (Pub.Papers), if therein. For material not recorded in the Public Papers, cite the Weekly Compilation of Presidential Documents (Weekly Comp. Pres. Doc.), published from 1965 to January 29, 2009, the Daily Compilation of Presidential Documents (Daily Comp. Pres. Doc.), published from January 29, 2009 to date, or the U.S. Code Congressional and Administrative News (U.S.C.C.A.N.) (rule 12.6).
Example:
Westlaw:
LexisNexis:
Online:
Library: