Jahn, Najko, Lisa Matthias, and Mikael Laakso. "Towards transparency of hybrid open access through publisher-provided metadata: An article-level study of Elsevier." Journal of the American Society for Information Science and Technology (2021).

This study has focused on hybrid Open Access (OA) uptake and invoicing at Elsevier. While Elsevier's hybrid OA uptake has slowly grown from 2015 to 2019, most of these articles were invoiced directly to authors, followed by articles invoiced through agreements with research funders or institutions.