[m] Einhard (Eginhard), Vita Caroli Magni.
[n] Codex Carolinus (Letters of the Popes to Frankish Kings).
Chapter V. Charlemagne
[b] Einhard (Eginhard), op. cit.
[c] Friedrich Wilhelm Benjamin von Giesebrecht, Geschichte der deutschen Kaiserzeit.
[d] Monk of Saint Gall, De Carolo Magno.
[e] J. Y. Sheppard, The Fall of Rome and the Rise of New Nationalities.
Chapter VI. Charlemagne’s Successors to the Treaty of Verdun
[b] Victor Duruy, Histoire du Moyen Âge.
[c] Leopold von Ranke, Weltgeschichte.