ff. 8r-53r of MS 139 contain the Summa introductoria by the mid-13th century Bonaguida d'Arezzo. Bonaguida composed a manual, of which these folios in MS 139 are a copy, on procedures of the medieval church court and law. It spans 45 folios in MS 139, ending on f. 53r with the words utilia plurima praetermisi ipsius auxilis fretus bonitatis. Explicit summa magistri bonajuncta. De aricio. Deo gracias.