Brown, Laura, et al. "Print Revenue and Open Access Monographs: A University Press Study." Ithaka S+R. Ithaka S+R. 19 September, (2023).
This report authored by members and representatives from the Association of University Presses, Ithaka S+R has used the aggregated data set of nearly 1,000 OA and non-OA titles by individual publishers to measure against their own historical data of sales for traditional, fully-paywalled monographs.