“In recent years, there has been a push to openly license citation metadata to better enable large-scale analyses and discoverability of scholarly work. The “Initiative for Open Citations” (I4OC),undefined launched in 2017, has led the way in helping publishers share citations to their works under a public domain CC0 license. As of early 2021, over a billion citations from one scholarly article to another are collected in public domain databases, a major shift from just a few years earlier.undefined These open databases provide the backbone for new discovery tools, and are used by academics training artificial intelligence tools. Open corpora like the Microsoft Academic Graph are themselves widely cited.undefined However, Microsoft Academic Graph will be shuttered in 2021; despite their importance, new citation projects are reliant on continued funding and support by their host, and longevity is not always guaranteed….
Wikidata is a freely licensed and editable online database of linked data, with 94 million items as of June 2021.undefined Like its sister project Wikipedia, it has a vibrant multilingual volunteer community that develops and maintains it, and is supported by the non-profit Wikimedia Foundation. Wikidata also includes bibliographic metadata: as of June 2021, nearly 40 million items on Wikidata represented publications, accounting for 43% of all items.undefined These are a combination of semi-automated uploads of citations from other open databases, items about notable publications that have their own Wikipedia articles, and items added manually by editors. Wikidata is also attractive for libraries, archives, and cultural institutions that want to make their metadata more openly available and reusable, and there are several ongoing projects to incorporate Wikidata into library and archival cataloging processes and connect Wikidata to new open knowledgebases….”