In plurimis is within the scope of WikiProject Catholicism, an attempt to better organize and improve the quality of information in articles related to the Catholic Church. For more information, visit the project page.CatholicismWikipedia:WikiProject CatholicismTemplate:WikiProject CatholicismCatholicism articles
I don't have a copy so I don't know how much time it spends on In plurimis or Leo XIII, but one possible place to start researching is Christopher J. Kellerman (2022). All Oppression Shall Cease : A History of Slavery, Abolitionism, and the Catholic Church. ISBN9781626984899. Kingdon (talk) 06:49, 13 November 2022 (UTC)[reply]