Both of these databases have international materials in addition to the landing pages noted below.
• Westlaw International Materials page.
• Lexis Advance International Sources page.
The Index to Foreign Legal Periodicals (IFLP) indexes articles from more than 450 foreign legal periodicals from 1985 to the present. The Index covers international law (public and private), comparative law, and municipal law of countries other than the United States, British Isles, and British Commonwealth.
Access restricted to FIU Law.
This database includes information dating back to 1690 on the history of international law subjects such as War & Peace, the Nuremberg Trials, Law of the Sea, International Arbitration, the Hague Conferences and Conventions and more. Includes more than 1,100 titles.
Scholarly articles on foreign and international law can be retrieved in the following databases:
Westlaw, you can search all secondary sources content or restrict your search to international law materials 
Lexis, in Content > Secondary materials, or using Practice Area > International Law or selecting a listed country from the International link in the 'Explore' selection tab or the View all Jurisdictions link.
HeinOnline, you can perform searches in several libraries:
Selection of International Law journals