The Dutch historian Ben Rekers authored two catalogues of Montano‘s letters in 1960 and 1973 (B. Rekers, "Benito Arias Montano Epistolario (1527-1598)", Hispanófila, 9 (1960), 25-37, and B. Rekers, Arias Montano (Madrid, 1973), p. 201-220. More recently (2002), we have published, also on paper, a revised inventory: Antonio Dávila Pérez, «El epistolario de Benito Arias Montano: catálogo provisional», De Gulden Passer, 80 (2002), 63-129.
We are currently working on a new corrected and updated inventory in digital format, as a complementary resource to the online publication project of Arias Montano's complete correspondence. The latest version has been published in 2019 in EMLO (Early Modern Letters Online)a project based at the University of Oxford, with the title «The Correspondence of Benito Arias Montano».