Jelaskan Kedua dari Erich dari Friuli

Hodgkin, Thomas. Italy and her Invaders. Clarendon Press: 1895.

Ross, James Bruce. "Two Neglected Paladins of Charlemagne: Erich of Friuli and Gerold of Bavaria." Speculum, Vol. 20, No. 2. (Apr., 1945), pp 212–235.

Wallach, Luitpold. "Alcuin on Virtues and Vices: A Manual for a Carolingian Soldier." Harvard Theological Review, Vol. 48, No. 3. (Jul., 1955), pp. 175–195.