Articles on foreign and comparative law can be found in general legal indexes and law journal databases such as Lexis Advance Quicklaw, WestlawNext Canada, HeinOnline, LegalTrac, Legal Source, SSRN, etc. The following indexes / databases focus particularly on foreign and comparative law.
Index to Australian and New Zealand articles and some UK, US and Canadian
HAPI (Hispanic American Periodicals Index)
Index to journal articles about Central and South America, Caribbean, Mexico, and Hispanics/Latinos in the US
Index to Foreign Legal Periodicals (IFLP), 1985-present (via HeinOnline)