Edward C. Phillips, S. I., The Correspondence of Father Christopher Clavius S. I. preserved in the Archives of the Pont. Gregorian University, 8 (1, 1939), Roma, Institutum Historium Societatis Jesu, 1939, pp. 193-222;

Paul Oskar Kristeller, Iter italicum. A finding list of uncatalogued or incompletely catalogued humanistic manuscripts of the Reinassance in italian and other libraries, London, Warburg Institute - Leiden, E.J. Brill, 1967, Vol. II, p. 136;

Christoph Clavius, Corrispondenza. Edizione critica a cura di Ugo Baldini e Pier Daniele Napolitani, Pisa 1992, 7 voll. in 14 fascicoli (University di Pisa. Dipartimento di matematica. Quaderni della Sezione di Didattica e Storia della Matematica) consultabile online al link: http://echo.mpiwg-berlin.mpg.de/content/mpiwglib/clavius;

Michael John Gorman, The scientific counter-revolution: mathematics, natural philosophy and experimentalism in Jesuit culture 1580-c1670, Ph. D. Thesis, European University, Institute - Department of History and Civilisation, Florence, 1998, p. 348