Abstract
This paper describes the Knowledge Base (KB) of the PALOMERA project, which contains data and documents relevant to policies regarding open access (OA) books in the European Research Area (ERA). The KB includes policy documents, grey literature, research articles, reports, and outputs of other projects, as well as interview transcripts with stakeholders. Data were collected during the first year of the project, covering the period from 2012 to 2022, while the surveys and interviews were conducted in 2023. The KB is openly accessible and can be reused for research and policymaking.