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1. Google Scholar

2. Index Copernicus International

3. SINTA

4. Garuda

5. Onesearch Indonesia

6. BASE

7. Harvard Library

8. Worldcat

9. Crossref

10. University of Oxford

11. UIC University Library

12. Jisc Library Hub Discover

13. Pusan National University Law Library

14. Nelson Mandela University

15. The University of Sheffield

16. Universiteitsbibliotheek Gent

17. Universiteit Leiden

18. Stanford University

19. Boston University