Finding literature
Database coverage
Which databases can be searched for you, what each one always or only sometimes returns, and which must be imported instead.
How to read the table
The table separates what a database always returns ("Guaranteed") from what it returns only sometimes ("Conditional"). A database that supplies abstracts for most articles has not promised abstracts, so plan screening around the Guaranteed column.
The entries are short codes. For example, metadata_search means the database can be searched, abstract means it returns abstracts, and fulltext_discovery means it reports where an open copy may exist, which is not the full text itself. The access class "open" means anyone may use the database; "licensed_api" means it needs your institution’s licence.
Optional databases are off until your organisation, which holds the licence, switches them on. The table is produced from the same list the search page uses, so it matches what you can select there.
Databases the platform can search, and what each one returns
PubMed
- Availability
- On by default
- Access class
- open
- Guaranteed
- metadata_search, metadata_lookup
- Conditional
- abstract, fulltext_discovery
- Paging
- offset, up to 200/page
OpenAlex
- Availability
- On by default
- Access class
- open
- Guaranteed
- metadata_search, metadata_lookup, citation_metadata, fulltext_discovery
- Conditional
- abstract
- Paging
- cursor, up to 200/page
Crossref
- Availability
- On by default
- Access class
- open
- Guaranteed
- metadata_search, metadata_lookup, citation_metadata
- Conditional
- abstract
- Paging
- cursor, up to 200/page
Semantic Scholar
- Availability
- On by default
- Access class
- open
- Guaranteed
- metadata_search, metadata_lookup, citation_metadata
- Conditional
- abstract, fulltext_discovery
- Paging
- offset, up to 100/page
Europe PMC
- Availability
- On by default
- Access class
- open
- Guaranteed
- metadata_search, metadata_lookup, citation_metadata, fulltext_discovery
- Conditional
- abstract, supplementary_discovery
- Paging
- cursor, up to 100/page
Scopus (official API)
- Availability
- Optional — off until licensed
- Access class
- licensed_api
- Guaranteed
- metadata_search, metadata_lookup, institutional_entitlement
- Conditional
- citation_metadata, abstract
- Paging
- offset, up to 25/page
Web of Science (official API)
- Availability
- Optional — off until licensed
- Access class
- licensed_api
- Guaranteed
- metadata_search, metadata_lookup, institutional_entitlement
- Conditional
- citation_metadata, abstract
- Paging
- offset, up to 50/page
Sources that arrive as a file
These sources cannot be searched for you. Each has its own reason, and each can still be used by exporting a file and importing it.
Import-only sources and how to export from them
Google Scholar
- Why it is import-only
- Google publishes no search API for Scholar, so there is nothing to connect to. Search it yourself, export the citations or follow a link out, and bring the file to the Imports page.
- How to export
- search → Save to My Library → Export → BibTeX
ResearchGate
- Why it is import-only
- ResearchGate's terms prohibit automated access, so this platform never queries or scrapes it. Open it in your own browser, under your own acceptance of its terms, and bring back a citation file or the DOI.
- How to export
- open the paper → copy the citation, or export it, and bring the file here
MDPI (a publisher, not a database)
- Why it is import-only
- MDPI is a PUBLISHER. It publishes journals; it does not index other publishers' work. Searching it answers 'what has MDPI published on this?', which is not the question a systematic search asks, and treating it as a database would bias a review towards one publisher's catalogue. Its articles are indexed by Crossref, OpenAlex, PubMed and Europe PMC, which this platform does query, so the right way to find them is a metadata search that covers every publisher at once.
- How to export
- open the article on the publisher's site → Export citation → RIS or BibTeX, and bring the file to the Imports page
Any other database
- Why it is import-only
- Anything with no connector here can still be searched in its own interface and imported as RIS, BibTeX or CSV. Nothing is lost by importing; the search itself is simply recorded as manual rather than executed by this platform.
- How to export
- export RIS / BibTeX / CSV with abstracts included
What the platform never does
The platform never reads a publisher website, a database website or a search-results page automatically. The optional databases use the official service your institution licenses, which is why they stay off until that licence is confirmed.
Optional databases that need a licence: Scopus (official API), Web of Science (official API).
Related
Searching the literature
Which databases are searched for you, which you search yourself, and what each search records.
Importing reference files
Bringing in papers by DOI or PubMed ID, from a pasted reference list, or from RIS, BibTeX, CSV and Excel files.
Removing duplicates
How duplicate papers are found, and why every merge waits for your confirmation.
Getting full text, legally
How full text is found automatically, what the platform will not fetch, and how the manual list works.