- Academic Index
- Bielefeld Academic Search Engine (BASE)
- Columbia International Affairs Online (CIAO)
- Directory of Open Access Journals (DOAJ)
- EBSCO Publishing Inc.
- EconLit
- EconPapers
- European Reference Index for the Humanities and Social Sciences (ERIH PLUS)
- European Sources Online
- Genamics JournalSeek
- IDEAS
- Index Islamicus
- Infomine
- International Bibliography of Book Reviews of Scholarly Literature in the Humanities and Social Sciences (IBR)
- International Bibliography of Periodical Literature in the Humanities and Social Sciences (IBZ)
- International Bibliography of the Social Sciences (IBSS)
- International Relations and Security Network (ISN)
- Lancaster Index to Defence & International Security Literature
- Peace Palace Library
- Research Papers in Economics (RePEc)
- Directory of Open Access Scholarly Resources (ROAD)
- Social Sciences Information Space (SOCIONET)
- Ulrich’s Periodicals Directory