indexing

1. Google Scholar
2. Crossref
3. Garuda (RistekDikti)
4. Bielefeld Academic Search Engine (BASE)
5. SINTA (Science Technology Index)
6. Scilit
7. WorldCat
8. Semantic Scholar
9. Scinapse

Library Indexing

1. Universiteit Leiden
2. Harvard Library
3. Georgetown University Library
4. Boston University