A papal diploma, still extant, shows that Count Borel and Bishop Octo or Otho of Ausona were at Rome in January 971, and, as all the other indications point to a corresponding year, enables us to fix the chronology of Gerbert's later life.
Among his works, which were first collectively published in 1867-1876, are Absolutissimus de octo orationis partium constructione libellus (Antwerp, 1530), Rudimenta Grammatices (London, 1539), Daily Devotions, Monition to a Godly Life, Epistolae ad Erasmum, and commentaries on different parts of the Bible.
His masterpiece, Libri octo de synodo diocesana, begun in Bologna, appeared during his pontificate.
In 1647 he published the treatise De vita, moribus, et doctrina Epicuri libri octo.
In 1672 appeared the De jure naturae et gentium, libri octo, and in 1675 a resume of it under the title of De officio hominis et civis.
In his writing Super potestate summi pontificis octo quaestionum decisions (1339-1342) Occam attacks the temporal supremacy of the pope, insists on the independence of kingly authority, which he maintains is as much an ordinance of.