2021 is just behind us. Since January is “the Monday of the months”, as F. Scott Fitzgerald once wrote[1], it’s a good time to take stock of what happened at OpenCitations during the past year.

“*What role does ‘open’ play in making this project special?”* This apparently easy, but not banal, question was asked in the Open Publishing Awards nomination form, and at OpenCitations we prefaced our answer to it by stating “For OpenCitations, ‘open’ is the crucial value and the final purpose.” We consider the free availability of bibliographic citation data to be a necessary condition for the establishment of an open knowledge graph, and

Guest post by Arcangelo Massari, University of Bologna In this post, Arcangelo Massari, who recently graduated in Digital Humanities and Digital Knowledge under Professor Silvio Peroni at the University of Bologna, shares the results of his master thesis. A particular problem in information retrieval is that of obtaining data from an evolving dataset, independent of the time at which that item of data was added, changed or removed.

No-one is quite sure of the total number of scholarly publications within the global corpus. Indeed that number will be strongly influenced by the degree to which, in addition to books and journal articles, one includes within the definition of scholarly publications ‘grey literature’ such as reports published by official bodies, patents, etc.

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.

What should an open scholarly infrastructure look like?

“The competitive benefits of closing access to citation data diminish with each new citation released to the public domain, but the benefits of open data remain. Going forward, citation data is almost completely public domain” . With these words, from the article “A tipping point for open citations data“ (July 15, 2021), Ian Hutchins celebrated the threshold crossing of one billion citations on public-domain databases in February 2021.

For the second year, OpenCitations has taken part in the LIBER annual conference.  **LIBER **(Ligue des Bibliothèques Européennes de Recherche – Association of European Research Libraries) is a network that gathers 440 research libraries, based in more than 40 countries all over the world, with the mission of supporting Europe’s research libraries

At the end of 2019, OpenCitations was selected by The Global Sustainability Coalition for Open Science Service (SCOSS) for presentation to the international scholarly community for crowd-sourced sustainability funding, along with the Public Knowledge Project (PKP) and the Directory of Open Access Books (DOAB). Since 2017, SCOSS has been helping identify non-commercial services essential to Open Science, and making

Today, we have published the bi-monthly release of COCI, the OpenCitations Index of Crossref open DOI-to-DOI citations.