Tax Analysts - Lexis: WWCASE (1890-current) - access worldwide tax court opinions
Tax Analysts - Lexis: WWLEG (1932-current)
Open access website contains bilateral treaties between the U.S. and foreign jurisdictions (in pdf).
RIA - Westlaw: RIA-TAXT (current) - treaties between the U.S. and other countries, technical explanations, Senate Committee reports, Secretary of State reports and other...
RIA - Westlaw: RIA-TAXTEX (current) - annotated analyses of treaties between the U.S. and other countries with citations to cases and rulings.
RIA - Westlaw: RIA-TREATIES (current) - treaties between the U.S. and others with legislative histories and editorial explanations (combination of RIA International Tax...
Tax Analysts - Lexis: WWPROC file (1950-current) - more than 150 tax treaties as amended by protocols, exchanges of notes, etc. (treaties in file and current form)..
Tax Analysts - Lexis: TAWTT (1828-current) - worldwide tax treaties and U.S. legislative histories; many English translations.
Tax Analysts - Lexis: WWFRCE (1910-current) - treaties that are currently in force organized by country and subject matter (i..e. coffee, sugar, etc).