van Espelo, Dorine (August 2013). "A testimony of Carolingian rule? The Codex epistolaris carolinus, its historical context, and the meaning of imperium in Early Medieval Europe". Early Medieval Europe. 21 (3): 254–282 (p.260). doi:10.1111/emed.12018. S2CID247659439.
van Espelo, Dorine (August 2013). "A testimony of Carolingian rule? The Codex epistolaris carolinus, its historical context, and the meaning of imperium in Early Medieval Europe". Early Medieval Europe. 21 (3): 254–282 (p.260). doi:10.1111/emed.12018. S2CID247659439.