US Code - Title 26: 26 U.S.C. Subtitle B — Federal Estate & Gift Tax.
US Code - Title 26: 26 U.S.C. Subtitle I, Ch. 98 — Trust Fund Code.

Internal Revenue Service: Decedents — PDF File. IRS Publication 502. Information regarding decedent's medical and dental expenses.
Internal Revenue Service: Personal Representatives — PDF File. IRS Publication 559. Information regarding survivors, executors, and administrators.
Internal Revenue Service: Rules for Survivors of Federal Employees — PDF File. (IRS Publication 721). From the Tax Guide to U.S. Civil Service Retirement Benefits: Rules regarding Salaries and Wages.
Internal Revenue Service: Unified Credit — PDF File. (IRS Publication 950). Introduction to information regarding Estate and Gift Taxes.
Uniform Probate Code — Provides links to the state statutes from states that have adopted the Uniform Probate Code.

Compilation of Social Security Laws — Includes the original Social Security Act, as amended. A list of laws which have amended the Act may be found in Volume II.
Social Security Administration: Government Pension Offset — Electronic Fact Sheet. Information on spouse or widow(er's) Social Security benefits that may be offset by receiving a government pension.
Social Security Administration: Receiving Benefits — Electronic Booklet in PDF. Available in English or Spanish. What You Need To Know When You Get Retirement Or Survivors Benefits.
Social Security Administration: Section on Survivor's Benefits — Publications related to survivor benefit rights and considerations. Available In English and Spanish.
Social Security Administration: Social Security Handbook — Summarizes Social Security programs and brief descriptions of related programs administered by other agencies.
Social Security Administration: Survivor's Benefits — Electronic Booklet in PDF. Available in English or Spanish. Information on including how survivor benefits are earned and other considerations.
Social Security Rulings and Acquiescence Rulings — Rulings by the Social Security Administration on Survivors, Disability, Supplemental Security Income, and Black Lung benefits.