More than 5,000 manuscripts attest the rhetoric, grammar, philosophy and theology lessons, taught along two centuries, and also the study of Greek and Latin classics, on astronomy, mathematics and physics, or of Latin, Greek, Hebrew and Arabic language. Many of these manuscripts were patiently copied by the auditores, others are autographs of well-known masters such as Famiano Strada, Christopher Clavius, Francisco Suarez, Roberto Bellarmino, Mutio Vitelleschi, Roger Joseph Boscovich, Juan Bautista Villalpando, Francisco de Toledo. In some cases the notes written for the lessons gave origin to important works, like the Bellarmino's Controversie, of which APUG owns a copy with a lot of handwritten notes by the author. Together with this material there are other important documents which attest the research and study activity which took place at the Roman College: the impressive Athanasius Kircher's correspondence, the Christopher Clavius's correspondence or the codex used by Francesco Sforza Pallavicino to write his "Istoria del Concilio di Trento".