Coverage of open citation data approaches parity with Web of Science and Scopus

Abstract

The information sources that are often used to monitor and to obtain a better understanding of the system of scholarly communication (such as Web of Science, Scopus, and Google Scholar) have historically been distributed under restrictive use licenses. However, in a scenario where science and scientific communication are undergoing a process of digital transformation, these models do not facilitate the development of new infrastructure that is better adapted to current and future needs. At the same time, these models hamper reproducibility. In recent years, a variety of open data sources, such as Microsoft Academic, Crossref, and others, have become available, providing easy access to large collections of metadata that were previously only available from closed sources. Citation data are one type of metadata provided by these open data sources. This study documents the significant growth in coverage of open citation data that has taken place between 2019 and 2021, and the events that have led to this point. These collections of open scholarly metadata have kick-started the development of a new ecosystem of scholarly information services. However, their fragility still poses a risk for downstream applications. Academic libraries could become important allies of open scholarly metadata initiatives.