1. Perpusnas : http://e-resources.perpusnas.go.id/
2. Portal Garuda : http://garuda.ristekbrin.go.id
3. Moraref : http://moraref.kemenag.go.id/
4. Google Scholar : https://scholar.google.co.id
5. Doaj : https://doaj.org/
6. Library Genesis : https://libgen.is/
7. Many Books : https://manybooks.net
8. Libri vox : https://Librivox.org/
9. Scribd : http://id.scribd.com/
10. International digital children's library : https://en.childrenslibrary.org/
11. Academia : https://Academia.edu.
12. Wiley Online Library : https://onlinelibrary.wiley.com
13. Science direct : https://sciencedirect.com/
14. Gutenberg : https://gutenberg.org/
15. Open Library : https://openlibrary.org/
16. Neliti : https://neliti.com/
17. Questia Public Library : https://Questia.com/
18. Wikibooks: https://Wikibooks.org/
19. Slide share : https://slideshare.net/
20. Free computer books : https://freecomputerbooks.net/
21. Academic microsoft : https://academic.microsoft.com/
22. Eureka Pendidikan : https://eurekapendidikan.com/
23. Research gate : https://researchgate.net/
24. OAPEN : https://oapen.org/
25. IEEE : https://ieeexplore.ieee.org/Xplore/home.jsp