Situs-situs Penyedia Referensi (Free)

1. Connected Papers
2. Digilib UINSBY
3. FreefullPDF
4. Garuda
5. Google Books
6. Google Scholar
7. Library Genesis
8. Lipi
9. Noor-Book
10. Perpustakaan Nasional
11. Researchgate
12. Science and Technology Index (Sinta)
13. Sciencedirect
14. Scopus
15. Semantic Scholar
16. The Directory of Open Access Journals (DOAJ)
17. Waqfeya