Leonardo understood how essential it was to his studies to find the sources of scientific and technological knowledge, and constantly sought to acquire such information.
His memorandums show that he frequented the Libraries of Santo Spirito and of San Marco in particular, where he noted the "chained books".
Based on over 300 sources, it has been possible to reconstruct Leonardo's "Ideal Library", which contained manuscripts and printed books that he mentions in lists in the Codex Atlanticus and Madrid Ms. II, as well as in various memorandums. He compiled these lists on the occasion of journeys and when, for instance, he left his books in Florence «in safekeeping at the monastery».
When he did not have them at hand, Leonardo could borrow or consult these books in monasteries and Florentine palaces. Some of them are now in the Biblioteca Medicea Laurenziana and the Biblioteca Nazionale Centrale di Firenze (BNCF), such as the Libro delle aree [Book of areas] by the Spanish-Jewish mathematician Abraham Bar Hyya Ha-Nasi, known as Savasorda, whose incipit was transcribed by Leonardo on the Weimar Folio, now in Malibu, California.
In these and other Florentine libraries, such as the Riccardiana and that of the Istituto e Museo di Storia della Scienza, are found apocryphal versions, facsimile editions, and rare publications of studies and research.
The documents on Leonardo's life and family are conserved mainly in the Florence State Archive, in the Opera del Duomo Archive, and in other repertories still partially unexplored.
