OpenCitations Access Tokens: how they work and why they are important

Since its inauguration in 2010, OpenCitations has always granted free access to its services to users throughout the world, with no requirement for registration or sign-up. Programmatic access to OpenCitations data can be obtained either via our SPARQL endpoints and our REST APIs. In addition, OpenCitations data – available in CSV, Scholix, and RDF formats – can be downloaded from data dumps made periodically and stored on Figshare, so as to enable large-scale analyses using the whole content of the data sets, and also be obtained via our user-friendly text-based search and browsing interfaces.

One of OpenCitations’ priorities is (and will always be) to keep its data globally open and available at zero cost and without restriction for third-party analysis and re-use. As a matter of sustainability, OpenCitations relies on financial support from the scholarly community, which includes those institutions that use OpenCitations data. However, OpenCitations has not so far had in place a proper system to monitor its users, and the main evidence of the impact of OpenCitations in different academic fields and countries has been incompletely obtained from direct contacts with our members and donors across the world, our collaborations with international projects, and the interactions on our social platforms (Twitter and LinkedIn).

We would now like to institute a system that enables us to follow the usage and assess the impact of OpenCitations more reliably. For this purpose, we are now happy to announce the launch of the OpenCitations Access Token System for access to the OpenCitations data and services.

An OpenCitations Access Token is an opaque character string that anonymously identifies a unique user of the OpenCitations APIs. OpenCitations assigns an access token only if authorized to do so by each user, who can request a token by inserting his/her email address into the access form and clicking “Get token”. Upon submission of such a request, each user will automatically receive a personal access token by email. Users can save their personal access token and reuse it every time calling the APIs of OpenCitations, by passing it as a value for the key access-token in the header of each API call. 

Obtaining and using an OpenCitations Access Token is thus easy. It only requires a simple form request, and then the insertion of your personal token into the API call header when using OpenCitations REST APIs. OpenCitations will not store users’ email addresses or any personal information, so that the users’ privacy will be totally safeguarded. The token system just provides a simple mechanism for identifying unique users, for which the use of IP addresses is insufficient.

Obtaining an OpenCitations Access Token will take the user only a few seconds and needs to happen only once. You can request your OpenCitations Access Token here

https://opencitations.net/accesstoken 

Use of an OpenCitations Access Token is not compulsory. However, token use will help OpenCitations incredibly, by enabling us to monitor the number of the unique users accessing our data and services, providing objective anonymized evidence of the number of institutions and researchers accessing our data either occasionally or on a regular basis, which we can then employ to demonstrate the usefulness of OpenCitations in the research environment. While the token system will initially be employed just for API calls (the most used service we offer), it will subsequently be extended to our other forms of data access.

OpenCitations exists for the people that use its data for research purposes every day, and thanks to their support. This is why obtaining precise knowledge of how many researchers and institutions are accessing our services is essential to us, since it will enable us to present the uniqueness and value of OpenCitations to new communities of stakeholders, and thus to make it possible to enlarge the already enthusiastic and diverse group of people and institutions supporting and using our Open Science Infrastructure.

To summarize: Getting and using an OpenCitations Access Token is voluntary, easy, and does not cost you anything. However, it will help OpenCitations a great deal. Please get your own token now, and use it next time you access OpenCitations. Thank you very much!

 

Additional 48 million citations in COCI, including references from IEEE 

We announce the August 2022 release of COCI, the OpenCitations Index of Crossref open DOI-to-DOI citations, which is based on open references to works with DOIs within the Crossref dump dated August 2022. This new release extends COCI with more than 48 million additional citations, giving a total number of more than 1.36 billion DOI-to-DOI citation links. 

This release includes citations from the articles published over the last four years by IEEE, whose bibliographic references were opened in June 2022. 

A fundamental role in pushing the commercial publishers to open their citation data was played by Crossref’s recent announcement to change its reference distribution policy, by making all its metadata open.  

Besides IEEE, COCI already includes the citation data derived from Elsevier (open via Crossref since December 2020) and from the last articles published by the American Chemical Society (whose references were opened in February 2021) 

You can find more information about COCI in our open-access article  

Ivan Heibi, Silvio Peroni & David Shotton (2019). Software review: COCI, the OpenCitations Index of Crossref open DOI-to-DOI citations. Scientometrics, 121 (2): 1213-1228. DOI: https://doi.org/10.1007/s11192-019-03217-6    

Finally, just a reminder that the bibliographic and citation data in COCI:  

    • can be queried using the OpenCitations Indexes SPARQL endpoint;  
    • can be retrieved by using the COCI REST API;  
    • can be searched by using the OpenCitations Indexes Search Interface;  
    • are also available as dumps on Figshare in CSV, N-Triples, and Scholix; and  
    • can be freely re-used for any purpose.

92 million new citations added to COCI

It’s been a month since the announcement of 1.09 Billion Citations available in the July 2021 release of COCI, the OpenCitations Index of Crossref open DOI-to-DOI citations.  

We’re now proud to announce the September 2021 release of COCI, which is based on open references to works with DOIs within the Crossref dump dated August 2021. This new release extends COCI with more than 92 Million additional citations, giving a total number of more than 1.18 Billion DOI-to-DOI citation links.

This latest release includes citations from the most recent articles published by the American Chemical Society, whose bibliographic references were opened in February 2021. The ACS back number citations will be available in the next COCI release, when a new processing of all the Crossref data will be completed.

You can find more information about COCI in our open-access article 

Ivan Heibi, Silvio Peroni & David Shotton (2019). Software review: COCI, the OpenCitations Index of Crossref open DOI-to-DOI citations. Scientometrics, 121 (2): 1213-1228. DOI: https://doi.org/10.1007/s11192-019-03217-6  

Finally, just a reminder that the bibliographic and citation data in COCI: 

  • can be queried using the OpenCitations Indexes SPARQL endpoint; 
  • can be retrieved by using the COCI REST API
  • can be searched by using the OpenCitations Indexes Search Interface; 
  • are also available as dumps on Figshare in CSV, N-Triples, and Scholix; and 
  • can be freely re-used for any purpose. 

Citations as First-Class Data Entities: The Open Citation Identifier Resolution Service

Requirements for citations to be treated as first-class data entities

In my introductory blog post, I listed five requirements for the treatment of citations as first-class data entities.  The fifth and final of these requirements is that there must be a Web-based identifier resolution service that takes the citation identifier as input and returns a description of the citation.

At the recent PIDapalooza Conference on persistent identifiers, held in Gerona, Spain, I described the Open Citation Identifier Resolution Service, the new resolution service for Open Citation Identifiers created and operated by OpenCitations [1].

In this post, I describe this Open Citation Identifier Resolution Service, which supports the resolution of Open Citation Identifiers not only of the citations documented in the OpenCitations Corpus (OCC), but also of open citations recorded in other bibliographic databases.

What is the Open Citation Identifier Resolution Service

The Open Citation Identifier Resolution Service runs on the OpenCitations server, presenting itself to the user as a web page with the URI http://opencitations.net/oci.

When a user enters a valid OCI and clicks the “Look up citation” button, this activates the resolution service, which, after a brief delay, returns information about the citation itself and about the citing and cited bibliographic resources, as shown in the following screen image (which for clarity omits the provenance data associated with this citation).

This information can optionally be returned to the user in a variety of other formats: RDF/XML, Turtle or JSON-LD.

Clicking on the links provided will return additional metadata held by the OpenCitations Corpus for the citing and the cited documents.  In the near future, this service will be integrated with LUCINDA, the forthcoming OCC browse interface, to present this information in a more user-friendly fashion.

Using the Resolution Service with citations in an external resource via a SPARQL endpoint

The Open Citation Identifier Resolution Service currently works for citations between bibliographic resources both within the OpenCitations Corpus and within external bibliographic databases, provided that the external service uses bibliographic resource identifiers having a unique numerical part, and provides a SPARQL endpoint to makes available information about bibliographic resources and the references they contain.

It can therefore resolve OCIs identifying citations within Wikidata, such as oci:01027931310-01022252312, where, as explained in the previous blog post, “010” is the assigned OCC supplier prefix for Wikidata.

Entering this OCI in the Open Citation Identifier Resolution Service pulls live data from the Wikidata SPARQL endpoint and returns the following information about that citation, as shown in the following screen image (which, again, omits for clarity the provenance data associated with that citation):

Clicking on the links provided here returns information about the relevant Wikidata entities.

Citing paper:

Cited paper:

How the Resolution Service works

The bibliographic database supplying the metadata for a particular citation identified by an OCI is specified by the assigned OCC supplier prefix that forms part of the OCI, as described in the previous blog post. Each OCI is thus specific for and unique within a particular bibliographic database.

The resolution service takes the OCI entered into the search box, recognises the supplier prefix specifying the bibliographic database holding the citation information, parses the OCI into the database identifiers for the citing and cited entities, and then sends an appropriate SPARQL query to interrogate the SPARQL endpoint of the relevant database. When that database has returned information about the citation itself and about the citing and cited bibliographic resources, this is displayed to the user as shown in screen images above – or in other RDF formats (Turtle, JSON-LD, RDF/XML) according to the request.

It is important to realize that no other databases are contacted during this resolution process, and that the quality and accuracy of the metadata retrieved by the Open Citation Identifier Resolution Service is the responsibility of the database hosting that citation.  The OCI Resolution Service does no more than retrieve this information, and does nothing to address possible errors or omissions in the metadata coming from the hosting database.

Using the Resolution Service with external citations via a REST API

While the resolution service presently works only to retrieve information from bibliographic databases having a SPARQL endpoint, we plan soon to extend this resolution service to work with information supplied by a bibliographic database via a REST API.

Coupled with the ability to create OCIs by numerical conversions of Digital Object Identifiers (DOIs), as explained in the previous blog post, the Open Citation Resolution Service could then be used to pull metadata live from the Crossref REST API for any of the ~350 million Crossref open references in which the cited paper as well as the citing paper has a DOI, and for which an OCI can thus be created.

Watch this space!

References

[1]     David Shotton (2018). Citations as first-class data entities. Open Citation Identifiers.  Conference presentation. PIDapalooza 2018, Girona, 23-23 January 2018. https://doi.org/10.6084/m9.figshare.5844972

Search OpenEdition Search

You will be redirected to OpenEdition Search