[4] From this time he began work amassing his Historia Imperialis ("Imperial History") a series of emperors' biographies, beginning with Augustus, in which his antiquarian bent and classical studies amended many misconceptions of ancient Roman history.
[5] Though he depended on Isidore's Etymologiae to a degree that would have been considered naive a century later, and on the Historia Augusta, deprecated nowadays, his marginal drawings of Roman coins show that numismatics had been brought to the historian's aid perhaps for the first time in this work.
Roberto Weiss has observed that "during the early Trecento [14th century] such a work as the Historia Imperialis could have been produced only in Verona", with the unrivalled library holdings of its cathedral chapter.
[7] By his careful reading of the Roman historian Suetonius, Giovanni detected that there were two authors named Pliny, not one, as had been believed previously.
He published his findings triumphantly in a tract (Brevis adnotatio de duobus Pliniis).