Printers Sweynheym and Pannartz issued the first edition of St. Augustine, De civitate dei from their press at the monastery of Subiaco, Italy. It is thought that the monks at the monastery participated in printing the edition.
The manuscript on which they based this printed edition remains preserved in the Monastery of St. Scholastica:
"That the codex was used for the printing is clearly shown by the frequent editorial corrections, the inky fingerprints, and the scored marks in the margins to indicate the end of the text page. The texts of the printed pages correspond almost exactly to these markings" (Wilson, The Making of the Nuremberg Chronicle  34).
This may be the earliest printed book for which the printer's manuscript remains extant. ISTC no. ia01230000.