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Version: 9.0.1

Crossref & Unpaywall

This section describes the procedure used to integrate the contents from Crossref and Unpaywall in the OpenAIRE Graph.

Data acquisition​

The dataset containing all the Crossref records is obtained via a complete data dump on a monthly basis. The Unpaywall dataset is no longer updated anymore but its latest snapshot (Dec 2021) is used to enrich the Crossref contents.

Process​

In the following we describe the process applied to the Crossref & the Unpaywall contents.

Crossref filtering​

Records in Crossref are ruled out according to the following criteria

  • have blank title, examples:
    • 10.1093/rheumatology/41.7.837
    • 10.1093/qjmed/95.7.430
    • 10.1371/journal.pone.0171434.g005
  • have one of the following publishers: "Test accounts", "CrossRef Test Account"
  • have authors matching the following invalid names: ",", "none none", "none, none", "none &na;", "(:null)", "test test test", "test test", "test", "&na; &na"
  • have "Addie Jackson" as author and "Elsevier BV" as publisher (empirically we say they are test records)
  • have not one of the following values in the field type : "book-section", "book", "book-chapter", "book-part", "book-series", "book-set", "book-track", "edited-book", "reference-book", "monograph", "journal-article", "dissertation", "other", "peer-review", "proceedings", "proceedings-article", "reference-entry", "report", "report-series", "standard", "standard-series", "posted-content", "dataset",
    • Example:
      • 10.1371/journal.pone.0171434.g005
      • 10.7554/elife.21052.049
      • 10.1371/journal.pcbi.1005379.s006

Records with type=dataset are mapped into OpenAIRE research products of type dataset. All others are mapped as OpenAIRE research products of type publication.

Mapping Crossref properties into the OpenAIRE Graph​

Properties in OpenAIRE research products are set based on the logic described in the following table:

OpenAIRE Research Product field pathCrossref path(s)Notes
iddoiid in the form doi_________::md5(doi)
dateofcollectionindexed.datetime
lastupdatetimestampindexed.timestamp
typetypeUsing the dnet:result_typologies vocabulary, we look up the instance.type synonym to generate one of the following main entities:
  • publication
  • dataset
originalIddoi, clinical-trial-number, alternative-id
pidThe scheme tells the type of PID, the value contains the actual value
pid.schemeDefault value: doi
pid.valuedoiThe doi is normalised and lower-cased
maintitletitle
subtitlesubtitle
authorauthorif available the sequence is mapped to rank and the ORCID is also mapped
author.nameauthor.given
author.surnameauthor.family
author.fullnameauthor.given author.family
author.rankbased on the order, starts from 1
author.pidonly if the ORCID is available
author.pid.id.schemeDefault 'pending_orcid' (meaning that it is not an id confirmed by ORCID)
author.pid.id.valueauthor.ORCID
author.pid.provenance.provenanceDefault 'Harvested'
author.pid.provenance.trustDefault '0.9'
descriptionabstract
subjectsubjectwith classid='keywords', i.e. no controlled vocabularies for Crossref subjects
publicationdateissued.datetime or, if not available, created.datetime
publisherpublisher
sourcesourceonly if the record is not of type book
sourceconcatenation of container-title.head + "ISBN: " + ISBN.headonly if the record is of type book
containerIt is set only for publications with information about the journal it was published in.
container.namecontainer-title.head
container.issnOnlineissn-type.valueif issn-type.type='electronic'
container.issnPrintedissn-type.valueif issn-type.type='print'
container.volvolume
container.sppagebefore '-'
container.eppageafter '-'
instanceOne instance is created with the DOI URL
instance.accessrightValues in instance.accessright.code and instance.accessright.label are set based on license and dateofacceptance:
- UNKNOWN: if the license is blank
- OPEN ACCESS: if the license is a CC license or an ACS license or an APA license (considered OPEN also by Unpaywall, see Unpaywall FAQ for details) or if OUP license, but only after 12 months from the publication date
- EMBARGO: OUP license, before 12 months from the publication date
- CLOSED: if there is a license not covered by the previous cases
instance.accessright.codeCode from the COAR vocabulary for access right
instance.accessright.labelOne of: OPEN, RESTRICTED, CLOSED, EMBARGO
instance.accessright.schemeScheme that defines the code and label, i.e. the URL to the COAR vocabulary for access right
instance.accessright.openAccessRouteonly if instance.accessright.value = 'OPEN ACCESS'. Default is hybrid. The route is fixed in subsequent phases of DOIBoost, namely when intersecting with Unpaywall and patching the hostedby via DOAJ and the Gold-ISSN list.
instance.licenselicense.URL If there is a license.content-version='vor', then this is used. Otherwise the first license entry is used.
instance.pidThe scheme tells the type of PID, the value contains the actual value
instance.pid.schemeDefault value: doi
instance.pid.valuedoiThe doi is normalised and lower-cased
instance.publicationdateissued.datetime or, if not available, created.datetime
instance.refereedset to peerReviewed only if relation.has-review.id is not empty, UNKNOWN otherwise.
instance.typesubtypemapped using the OpenAIRE vocabulary for research products typologies
instance.urldoiFull URL of the DOI

All other fields of the Json schema not mentioned in the table contain empty values.

All the records from Crossref are related to the datasource with name=Crossref and id=openaire____::081b82f96300b6a6e3d282bad31cb6e2

Possible improvements:

  • map clinical-trial-number and alternative-id in alternateIdentifiers?
  • Verify if Crossref has a property for language, country, container.issnLinking, container.iss, container.edition, container.conferenceplace and container.conferencedate
  • Different approach to set the refereed field and improve its coverage?

Links to funding available in Crossref are mapped as funding relationships (ResearchProduct -- isProducedBy -- Project) applying the following mapping:

FunderGrant codeLink to
DOI: {10.13039/100010663, 10.13039/100010661, 10.13039/501100007601, 10.13039/501100000780, 10.13039/100010665} or name: 'European Union’s Horizon 2020 research and innovation program'series of 4-9 digits in awardLink to H2020 project
DOI: {10.13039/100011199, 10.13039/100004431, 10.13039/501100004963, 10.13039/501100000780}series of 4-9 digits in awardLink to FP7 project
DOI: 10.13039/501100000781 OR name: 'European Union's'series of 4-9 digits in awardLink to FP7 or H2020 project
DOI: 10.13039/100000001awardLink to NSF project
DOI: 10.13039/501100001665 OR name: {'The French National Research Agency (ANR)', 'The French National Research Agency'}awardLink to ANR project
DOI: 10.13039/501100002341awardLink to Academy of Finland project
DOI: 10.13039/501100001602award, removing the initial 'SFI' if presentLink to SFI project
DOI: 10.13039/501100000923awardLink to ARC project
DOI: 10.13039/501100000038award ignore: we cannot map the project codes in Crossref to project codes in OpenAIRELink to NSERC (unidentified project)
DOI: 10.13039/501100000155award ignore: we cannot map the project codes in Crossref to project codes in OpenAIRELink to SSHRC (unidentified project)
DOI: 10.13039/501100000024award ignore: we cannot map the project codes in Crossref to project codes in OpenAIRELink to CIHR (unidentified project)
DOI: 10.13039/501100002848 OR name :'CONICYT, Programa de Formación de Capital Humano Avanzado'awardLink to CONICYT project
DOI: 10.13039/501100003448series of 4-9 digits in awardLink to GSRT project
DOI: 10.13039/501100010198awardLink to SGOV project
DOI: 10.13039/501100004564series of 4-9 digits in awardLink to MESTD project
DOI: 10.13039/501100003407awardLink to MIUR project. Since OpenAIRE has a small subset of MIUR projects, a link to the MIUR funder (unidentified
project) is also generated
DOI: {10.13039/501100006588, 10.13039/501100004488}award, removing 'Project No' and 'HRZZ' prefix, if presentLink to HRZZ or MZOS project
DOI: 10.13039/501100006769awardLink to Russian Science Foundation project
DOI: 10.13039/501100001711award after '_' and before '/'Link to SNSF project
DOI: 10.13039/501100004410awardLink to TUBITAK project
DOI: 10.10.13039/100004440 or name: Wellcome Trust Masters FellowshipawardLink to Wellcome Trust specific project and to the unidentified project.

Intersect Crossref with UnpayWall by DOI​

The fields we consider from UnpayWall are:

  • is_oa
  • best_oa_location
  • oa_status

The records of Crossref that intersect by DOI with UnpayWall records are enriched with one additional instance with the following properties:

OpenAIRE Research Product field pathUnpaywall field pathNotes
instancecreated only if is_oa and a best_oa_location is available
instance.accessrightdefault value Open Access: we do not add instances if UnpayWall says there is no open version
instance.accessright.codeOpen Access code from the COAR vocabulary for access right
instance.accessright.labelAlways OPEN
instance.accessright.schemeScheme that defines the code and label, i.e. the URL to the COAR vocabulary for access right
instance.accessright.openAccessRouteoa_status
instance.urlbest_oa_location
instance.licensebest_oa_location.license
instance.pidThe scheme tells the type of PID, the value contains the actual value
instance.pid.schemeDefault value: doi
instance.pid.valuedoiThe doi is normalised and lower-cased

For the definition of UnpayWall's oa_status refer to the Unpaywall FAQ

The record will also feature a relation to the UnpayWall data source: name="UnpayWall", id=openaire____::8ac8380272269217cb09a928c8caa993.