Entities and Fields Reference by Source

This document details the retrievable objects and their attributes for each bibliographic source.

Table of Contents

• Semantic Scholar
• PubMed / NCBI
• Europe PMC
• Unpaywall
• OpenCitations
• DataCite
• DOAJ
• Zenodo
• DBLP
• bioRxiv / medRxiv
• CORE
• Paid Sources

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Semantic Scholar

Base URL: https://api.semanticscholar.org/graph/v1

Available Entities

Entity	Endpoints	Description
Paper	/paper/{id}, /paper/search, /paper/batch	Scientific publications
Author	/author/{id}, /author/search, /author/batch	Author profiles
Citation	/paper/{id}/citations	Incoming citations
Reference	/paper/{id}/references	Outgoing references
Snippet	/snippet/search	Text excerpts

Paper - Available Fields

Field	Type	Description	Always Returned
paperId	string	Unique SHA identifier	✅
title	string	Article title	✅
corpusId	integer	Secondary numeric identifier	❌
externalIds	object	DOI, ArXiv, MAG, ACL, PMID, PMCID, DBLP	❌
url	string	Semantic Scholar page URL	❌
abstract	string	Abstract	❌
venue	string	Publication venue name	❌
publicationVenue	object	Venue details (id, name, type, URLs)	❌
year	integer	Publication year	❌
publicationDate	string	Full date (YYYY-MM-DD)	❌
publicationTypes	array	Classification (Review, JournalArticle, Conference)	❌
referenceCount	integer	Number of references	❌
citationCount	integer	Number of citations	❌
influentialCitationCount	integer	High-impact citations	❌
isOpenAccess	boolean	Open Access status	❌
openAccessPdf	object	PDF URL, status, license	❌
fieldsOfStudy	array	Academic categories	❌
s2FieldsOfStudy	array	Detailed classifications with sources	❌
journal	object	Name, volume, pages	❌
citationStyles	object	BibTeX format	❌
authors	array	Author list	❌
citations	array	Citing articles	❌
references	array	Cited articles	❌
embedding	object	SPECTER vector (v1 or v2)	❌
tldr	object	AI-generated summary	❌

Author - Available Fields

Field	Type	Description	Always Returned
authorId	string	Unique identifier	✅
name	string	Full name	✅
externalIds	object	ORCID, DBLP	❌
url	string	S2 profile URL	❌
affiliations	array	Organizations	❌
homepage	string	Personal website	❌
paperCount	integer	Number of publications	❌
citationCount	integer	Total citations	❌
hIndex	integer	h-index	❌
papers	array	Publications	❌

Supported Identifiers

paperId (SHA), CorpusId:<id>, DOI:<doi>, ARXIV:<id>, MAG:<id>,
ACL:<id>, PMID:<id>, PMCID:<id>, URL:<url>

---

PubMed / NCBI

Base URL: https://eutils.ncbi.nlm.nih.gov/entrez/eutils/

E-utilities Endpoints

Endpoint	Function	Output
einfo.fcgi	Database metadata	Database list, indexed fields
esearch.fcgi	Search	UIDs, count, query_key
efetch.fcgi	Retrieval	Complete records
esummary.fcgi	Summaries	DocSums (lightweight metadata)
elink.fcgi	Links	Linked UIDs, external links
epost.fcgi	Upload UIDs	Session History
espell.fcgi	Spell check	Suggestions
ecitmatch.cgi	Citation match	PMIDs

Main Databases

Database	Content	Records
pubmed	Biomedical literature	35M+
pmc	Open Access full text	8M+
gene	Genes	-
protein	Proteins	-
nucleotide	DNA/RNA sequences	-
taxonomy	Taxonomy	-
clinvar	Clinical variants	-

PubMed Article - Available Fields

Field	Description	Via
PMID	PubMed identifier	efetch
Title	Title	efetch, esummary
Abstract	Abstract	efetch
AuthorList	Authors (name, affiliation, ORCID)	efetch
Journal	Journal title, ISSN, volume, issue	efetch
PubDate	Publication date	efetch
ArticleType	Type (Review, Research, etc.)	efetch
MeshHeadingList	MeSH terms	efetch
KeywordList	Author keywords	efetch
GrantList	Funding	efetch
ReferenceList	Cited references	efetch
DOI	Digital Object Identifier	efetch
PMC	PubMed Central ID	elink

Output Formats

Format	Parameter	Description
XML PubMed	rettype=xml	Complete native format
MEDLINE	rettype=medline	Bibliographic format
Abstract	rettype=abstract	Plain text
JSON	retmode=json	For esearch, esummary

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Europe PMC

Base URL: https://www.ebi.ac.uk/europepmc/webservices/rest/

Endpoints

Endpoint	Description
/search	Publication search
/fields	Available search fields
/{source}/{id}/citations	Incoming citations
/{source}/{id}/references	References
/{source}/{id}/databaseLinks	Database links
/{source}/{id}/textMinedTerms	Text-mining annotations
/{id}/fullTextXML	Full text XML
/{id}/supplementaryFiles	Supplementary files

Article - Available Fields

Field	Type	Description
id	string	Identifier (PMID or PMC)
source	string	MED, PMC, PAT, etc.
title	string	Title
authorString	string	Formatted authors
authorList	array	Detailed authors
journalTitle	string	Journal title
pubYear	integer	Year
abstractText	string	Abstract
doi	string	DOI
isOpenAccess	boolean	OA status
inEPMC	boolean	Full text in EPMC
citedByCount	integer	Citation count
hasReferences	boolean	References available
grantsList	array	Funding
meshHeadingList	array	MeSH terms
chemicalList	array	Chemical substances

Text-mining Annotations

Type	Description
DISEASE	Diseases
GENE_PROTEIN	Genes/Proteins
ORGANISM	Organisms
CHEMICAL	Chemical compounds
GO_TERM	Gene Ontology

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Unpaywall

Base URL: https://api.unpaywall.org/v2/

Single Endpoint

GET /{doi}?email=your@email.com

Work - Available Fields

Field	Type	Description
doi	string	DOI
doi_url	string	Resolved DOI URL
title	string	Title
genre	string	Type (journal-article, book-chapter, etc.)
is_paratext	boolean	Editorial content
published_date	string	Publication date
year	integer	Year
journal_name	string	Journal name
journal_issns	string	ISSNs
journal_issn_l	string	ISSN-L
publisher	string	Publisher
is_oa	boolean	Open Access?
oa_status	string	gold, green, hybrid, bronze, closed
has_repository_copy	boolean	Repository copy
best_oa_location	object	Best OA location
first_oa_location	object	First OA location
oa_locations	array	All OA locations
oa_locations_embargoed	array	Embargoed locations
updated	string	Last update
data_standard	integer	Data version
z_authors	array	Authors (via Crossref)

OA Location - Sub-object

Field	Type	Description
url	string	Page URL
url_for_pdf	string	Direct PDF URL
url_for_landing_page	string	Landing page
host_type	string	publisher, repository
license	string	CC-BY, CC-BY-NC, etc.
version	string	publishedVersion, acceptedVersion, submittedVersion
evidence	string	Detection source
pmh_id	string	OAI-PMH ID
endpoint_id	string	Endpoint ID
repository_institution	string	Repository institution

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OpenCitations

Base URL: https://api.opencitations.net/index/v2

Endpoints

Endpoint	Description
/citation/{oci}	Citation by OCI
/citations/{id}	Incoming citations
/references/{id}	Outgoing references
/citation-count/{id}	Citation count
/reference-count/{id}	Reference count

Citation - Available Fields

Field	Type	Description
oci	string	Open Citation Identifier
citing	string	Citing article IDs
cited	string	Cited article IDs
creation	string	Creation date (ISO 8601)
timespan	string	Time between publication (PnYnMnD)
journal_sc	string	Journal self-citation (yes/no)
author_sc	string	Author self-citation (yes/no)

Supported Identifiers

DOI, PMID, PMCID, OMID (OpenCitations ID), ISSN (for venues)

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DataCite

Base URL: https://api.datacite.org/

Main Endpoints

Endpoint	Description
/dois	DOI search
/dois/{doi}	Specific DOI
/clients	Member organizations
/providers	Providers

DOI Record - Available Fields

Field	Type	Description
doi	string	DOI
prefix	string	DOI prefix
suffix	string	Suffix
identifiers	array	Alternative identifiers
creators	array	Creators (name, affiliation, ORCID, ROR)
titles	array	Titles (main, alternative)
publisher	string	Publisher
publicationYear	integer	Year
resourceType	object	Type (Dataset, Software, etc.)
subjects	array	Subjects
contributors	array	Contributors
dates	array	Dates (created, issued, updated)
language	string	Language (ISO 639)
types	object	Resource types
relatedIdentifiers	array	Links to other resources
sizes	array	Sizes
formats	array	File formats
version	string	Version
rights	array	Licenses
descriptions	array	Descriptions
geoLocations	array	Geographic locations
fundingReferences	array	Funding
url	string	Landing page
contentUrl	string	Content URL
xml	string	XML metadata (Base64)
viewCount	integer	View count
downloadCount	integer	Downloads
citationCount	integer	Citations
state	string	findable, registered, draft
created	string	Creation date
registered	string	Registration date
updated	string	Last update

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DOAJ

Base URL: https://doaj.org/api/

Endpoints

Endpoint	Description
/search/articles/{query}	Article search
/search/journals/{query}	Journal search
/articles/{id}	Article by ID
/journals/{issn}	Journal by ISSN
/bulk/articles	Batch article upload

Article (bibjson) - Available Fields

Field	Type	Description
id	string	DOAJ ID
bibjson.title	string	Title
bibjson.identifier	array	DOI, other IDs
bibjson.journal.title	string	Journal title
bibjson.journal.issns	array	ISSNs
bibjson.journal.publisher	string	Publisher
bibjson.journal.country	string	Country
bibjson.author	array	Authors
bibjson.abstract	string	Abstract
bibjson.keywords	array	Keywords
bibjson.year	string	Year
bibjson.month	string	Month
bibjson.start_page	string	Start page
bibjson.end_page	string	End page
bibjson.link	array	Links (PDF, HTML, ePUB, XML)
bibjson.subject	array	Subjects
created_date	string	Creation date
last_updated	string	Last update

Journal (bibjson) - Available Fields

Field	Type	Description
id	string	DOAJ ID
bibjson.title	string	Title
bibjson.alternative_title	string	Alternative title
bibjson.identifier	array	pISSN, eISSN
bibjson.publisher	object	Publisher, country
bibjson.institution	object	Institution
bibjson.oa_start	integer	OA start year
bibjson.apc	object	Publication fees
bibjson.license	array	Licenses
bibjson.subject	array	Subjects
bibjson.language	array	Languages
bibjson.ref.aims_scope	string	Aims and scope URL
bibjson.ref.author_instructions	string	Author instructions URL

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Zenodo

Base URL: https://zenodo.org/api/

Main Endpoints

Endpoint	Description
/records	Published records search
/records/{id}	Specific record
/deposit/depositions	Deposit management
/licenses	Available licenses
/communities	Communities

Record - Available Fields

Field	Type	Description
id	integer	Zenodo ID
doi	string	DOI
doi_url	string	DOI URL
conceptdoi	string	Concept DOI (all versions)
conceptrecid	integer	Concept ID
created	string	Creation date
modified	string	Last modification
metadata.title	string	Title
metadata.description	string	Description (HTML)
metadata.upload_type	string	publication, dataset, software, etc.
metadata.publication_type	string	article, preprint, thesis, etc.
metadata.publication_date	string	Publication date
metadata.creators	array	Creators (name, affiliation, orcid, gnd)
metadata.contributors	array	Contributors
metadata.keywords	array	Keywords
metadata.subjects	array	Controlled subjects
metadata.related_identifiers	array	Related identifiers
metadata.grants	array	Funding
metadata.communities	array	Communities
metadata.license	object	License
metadata.access_right	string	open, embargoed, restricted, closed
metadata.embargo_date	string	Embargo end date
metadata.journal.title	string	Journal (if article)
metadata.journal.volume	string	Volume
metadata.journal.issue	string	Issue
metadata.journal.pages	string	Pages
metadata.conference.title	string	Conference
metadata.conference.dates	string	Conference dates
metadata.conference.place	string	Location
metadata.conference.url	string	Conference URL
metadata.imprint.publisher	string	Publisher
metadata.imprint.isbn	string	ISBN
metadata.thesis.university	string	University
metadata.thesis.supervisors	array	Supervisors
metadata.version	string	Version
metadata.language	string	Language (ISO 639-3)
metadata.locations	array	Geo locations
metadata.dates	array	Additional dates
metadata.method	string	Methodology
files	array	Files (id, filename, size, checksum)
owners	array	Owners
stats	object	Statistics (views, downloads)

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DBLP

Base URL: https://dblp.org/

Endpoints

Endpoint	Description
/search/publ/api	Publication search
/search/author/api	Author search
/search/venue/api	Venue search
/pid/{pid}.xml	Publication by ID
/rec/{key}.xml	Record by key

Publication - Available Fields

Field	Type	Description
key	string	Unique DBLP key
title	string	Title
authors	array	Authors
venue	string	Conference/Journal
year	integer	Year
type	string	article, inproceedings, book, etc.
doi	string	DOI
ee	string	Electronic URL
url	string	DBLP URL
pages	string	Pages
volume	string	Volume
number	string	Issue

Author - Available Fields

Field	Type	Description
pid	string	Person ID
name	string	Name
aliases	array	Alternative names
url	string	Profile URL
affiliations	array	Affiliations
notes	array	Notes

Venue - Available Fields

Field	Type	Description
venue	string	Full name
acronym	string	Acronym
type	string	journal, conference, workshop
url	string	DBLP URL

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bioRxiv / medRxiv

Base URL: https://api.biorxiv.org/

Endpoints

Endpoint	Description
/details/{server}/{interval}	Metadata by period
/pubs/{server}/{interval}	Published preprints
/pub/{interval}	Publications (bioRxiv)
/publisher/{prefix}/{interval}	By publisher
/funder/{server}/{interval}/{ror}	By funder
/sum/{interval}	Statistics
/usage/{interval}/{server}	Usage metrics

Preprint - Available Fields

Field	Type	Description
doi	string	Preprint DOI
title	string	Title
authors	string	Authors (text format)
author_corresponding	string	Corresponding author
author_corresponding_institution	string	Corresponding institution
date	string	Publication date
version	string	Version (1, 2, etc.)
type	string	Preprint type
license	string	License
category	string	Scientific category
jatsxml	string	JATS XML URL
abstract	string	Abstract
published	string	Published version DOI
server	string	biorxiv or medrxiv

Published Preprint - Additional Fields

Field	Type	Description
biorxiv_doi	string	Preprint DOI
published_doi	string	Published DOI
published_journal	string	Publication journal
published_date	string	Publication date
preprint_platform	string	Origin platform

Funder Data - Additional Fields

Field	Type	Description
funding.name	string	Funder name
funding.id	string	Funder ID
funding.id-type	string	ID type (ROR, Crossref)
funding.award	string	Grant number

Usage Statistics

Field	Type	Description
month	string	Month
abstract_views	integer	Abstract views
full_text_views	integer	Full text views
pdf_downloads	integer	PDF downloads
*_cumulative	integer	Cumulative totals

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CORE

Base URL: https://api.core.ac.uk/v3/

Endpoints

Endpoint	Description
/search/works	Works search (deduplicated)
/search/outputs	Outputs search (raw)
/search/data-providers	Provider search
/search/journals	Journal search
/works/{id}	Specific work
/outputs/{id}	Specific output
/outputs/{id}/download	PDF download

Work - Available Fields

Field	Type	Description
id	integer	CORE ID
doi	string	DOI
title	string	Title
abstract	string	Abstract
authors	array	Authors
contributors	array	Contributors
publisher	string	Publisher
journals	array	Journals
yearPublished	integer	Year
publishedDate	string	Publication date
acceptedDate	string	Acceptance date
depositedDate	string	Deposit date
documentType	string	Document type
fullText	string	Full text
downloadUrl	string	Download URL
sourceFulltextUrls	array	Source URLs
citationCount	integer	Citations
references	array	References
fieldOfStudy	array	Fields
identifiers	array	All identifiers
arxivId	string	ArXiv ID
magId	string	Microsoft Academic ID
pubmedId	string	PubMed ID
oaiIds	array	OAI-PMH IDs
dataProviders	array	Providers
outputs	array	Related outputs
links	array	Links
createdDate	string	Creation date
updatedDate	string	Last update

Output - Additional Fields

Field	Type	Description
repositories	array	Source repositories
repositoryDocument	object	Repository document
fulltextStatus	string	Full text status
language	string	Language
license	string	License
subjects	array	Subjects
tags	array	Tags
sdg	array	Sustainable Development Goals
oai	string	OAI identifier
setSpecs	array	OAI-PMH sets

Data Provider - Available Fields

Field	Type	Description
id	integer	CORE ID
name	string	Name
institutionName	string	Institution
type	string	Type (repository, journal)
homepageUrl	string	Website URL
oaiPmhUrl	string	OAI-PMH URL
email	string	Contact
location	object	Location
logo	string	Logo URL
rorId	string	ROR ID
openDoarId	string	OpenDOAR ID
software	string	Software (DSpace, EPrints)
metadataFormat	string	Metadata format

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Paid Sources

Scopus

Entity	Key Fields
Document	EID, DOI, title, authors, abstract, affiliation, citedby_count, keywords, subject_areas
Author	Author ID, name, affiliation, h-index, document_count, cited_by_count, orcid
Affiliation	Affiliation ID, name, city, country, document_count

Web of Science

Entity	Key Fields
Document	UID, DOI, title, authors, source, year, keywords, times_cited
Journal	ISSN, title, impact_factor, category, publisher

IEEE Xplore

Entity	Key Fields
Document	Article number, DOI, title, authors, abstract, publication_title, conference_dates, content_type
Standard	Standard number, title, status, committee

Dimensions

Entity	Key Fields
Publications	id, doi, title, authors, abstract, journal, year, citations_count, altmetrics
Grants	id, title, funder, amount, start_year, investigators
Patents	id, title, inventors, assignees, filing_date, jurisdiction
Clinical Trials	id, title, phase, conditions, interventions, registry
Datasets	id, doi, title, repository, year
Policy Documents	id, title, publisher, year

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Coverage Comparison

Source	Publications	Authors	Citations	Full Text	Funding
Semantic Scholar	✅ 200M+	✅	✅ Rich	❌	❌
PubMed	✅ 35M+	✅	❌	Via PMC	✅
Europe PMC	✅ 40M+	✅	✅	✅ 10M+	✅
Unpaywall	❌	❌	❌	✅ URLs	❌
OpenCitations	❌	❌	✅ 1.4B+	❌	❌
DataCite	✅ 50M+	✅	✅	❌	✅
DOAJ	✅ 9M+	✅	❌	❌	❌
Zenodo	✅ 3M+	✅	❌	✅	✅
DBLP	✅ 6M+	✅	❌	❌	❌
bioRxiv	✅ 250k+	✅	❌	✅	✅
CORE	✅ 300M+	✅	✅	✅	❌