1. DOAJ  

 

2. GOOGLE SCHOLAR

 

3. Crossref

 

4. Dirctory of Open Access Scholarly Resources (Road)  

 

5. EBSCO Open Science Directory 

 

 6. BASE (Biefeld Academic Search Engine)

 

7. Indonesia OneSearch by Perpusnas 

 

 

8. WorldCat 

 

9. University of OXFORD

 

10. Harvard Library

 

11. Scilit

 

12. BU Libraries Search

13.  Sherpa/RoMEO

14. JournalTOCs

15. Leiden University Library

16. Copac JIsc

17.  Collective Goods Research & Explore (CORE)

18. The University of Sheffield

19. Stanford University

20. Vancouver Public Library

21. University Public