The Open Citations Movement

Purpose
A
bibliographic citation is a conceptual directional link from a citing entity to a cited entity, for the purpose of acknowledging or ascribing credit for the contribution made by the author(s) of the cited entity, as stated by Newton in his motto – “If I have seen further it is by standing on the shoulders of Giants” (Newton, 1675). The citing and cited entities may be scholarly publications, online documents, blog posts, datasets, or any other authored entity capable of giving or receiving citations. While the act of citing by the author may be the work of a moment, the citation itself, once the citing work is published, becomes an enduring component of the academic ecosystem.

This abstract introduces the uptakes and the benefits of releasing a huge set of
open citation data as public domain material. In particular, we introduce the main events that have characterised this movement towards opening citations by discussing what has happened with the establishment of the Initiative for Open Citations. We accompany the discussion with examples and projects that were born as a consequence of this movement, including some contributions from the Digital Humanities domain.

Definition
As stated by Peroni and Shotton (Peroni and Shotton, 2018), a bibliographic citation is an
open citation when the data needed to define the citation are FAIR (Wilkinson et al., 2016) and, in particular, are:

Structured – expressed in one or more machine-readable formats, such as XML, JSON, RDF;
Separate – available without the need to access the source bibliographic entity (e.g. the article or book) in which the citation is defined;
Open – freely accessible and reusable without restrictions, for example by publication under the CC0 1.0 Universal waiver/license or generally released as public domain material;
Identifiable – the citing and cited entities described by an open citation must be clearly identified by using a specific persistent identifier scheme (e.g. a DOI) or a URL;
Available – there must exist a mechanism to resolve the identifiers of the citing and cited entity to obtain the
basic metadata of both the entities, i.e. sufficient information to create or retrieve textual bibliographic references for each of the entities.

Findings
The first project that introduced the open availability of open bibliographic and citation data by means of Semantic Web (Linked Data) technologies was the OpenCitations Corpus, in 2010, which was one of the outputs of the Open Citations Project funded by Jisc (Shotton, 2013). However, the availability of open citation data recently changed drastically with the establishment of the
Initiative for Open Citations (I4OC,
https://i4oc.org), in April 2017.

The Initiative was born with the idea of promoting the release of open citation data and has explicitly asked the main scholarly publishers, who deposited their citations on Crossref (https://crossref.org), to release them in the public domain. As a result, now we have several millions of citation data openly available on the Web, a list of important stakeholders – such as libraries, consortiums, projects, organizations, companies, and, in particular, founders (Shotton, 2018) – supporting the movement, and several international events (e.g. the
Workshop on Open Citations and
WikiCite 2018) organised for promoting the open availability of citation data. Several projects and datasets have been released so far so as to leverage the open citation data available online. As a result, there is a growing list of publishers that release their citation data in Crossref, and these citation data also come from important journals in the Digital Humanities field such as
Digital Scholarship in the Humanities published by the Oxford University Press.

Research implications
Several citation indexes, such as Clarivate Analytics's Web of Science and Elsevier's Scopus, make available citation data in a structured form. However, their access is possible only by paying expensive fees of several hundreds of dollars (Chadegani, 2017). In addition, the license associated with these data is quite restrictive and does not allow one to reuse them for any purpose.
The current coverage of the open citation data available is still far from being competitive with the aforementioned well-known proprietary citation indexes (van Eck et al., 2018). However, open citation data already allows researchers – particularly those ones working in institutions that cannot pay exaggerate fees to access the aforementioned commercial indexes – to work on citation data and perform interesting and important discoveries.

Practical implications
Collecting all the citation data from the whole scientific knowledge in just one centralised repository is practically unfeasible. The only long-term solution is to set up a federation of decentralised citation databases that can co-operate with each other by means of Web technologies, as suggested in (COAR Next Generation Repositories WG, 2017) – see, for instance, the RDF datasets made available by
Wikidata and
OpenCitations.

Social implications
Citations have been one of the core parts of the scholarly system since the beginning. However, they are not currently seen only as an acknowledgement medium, but rather have recently been used according to additional functions. For instance, citation networks can be characterised (a)
topologically by defining the connected graph between citing and cited entities during time (Chawla, 2017), (b)
sociologically such as for identifying odd conducts in or elitist access paths to scientific research (Sugimoto et al., 2017), (c) according to
quantitative rationales by creating citation-based metrics for evaluating the impact of an idea or a person (Schiermeier, 2017), and (d) defining a sort of
economic value, i.e. the currency with which a researcher addresses his/her own academic sustenance (Molteni, 2017).

Having open citation data available is fair, since it enables anyone, from scholars to citizen scientists, to study and follow the evolution of science during time according to all the aforementioned perspectives.

Value
Open citation data makes a positive disruption in the world of scholarly communication since they change entirely how we face to science, its evolution, and all the related context, such as research assessment evaluations, science of science, bibliometrics, and future scientific discoveries in all the domains – including the Digital Humanities domain.

Bibliography

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