[c] H. Stebbing, op. cit.
[d] J. B. Mullinger, op. cit.
[e] H. H. Milman, op. cit.
[f] V. Duruy, op. cit.
[g] James Bryce, The Holy Roman Empire.
[h] Roger of Hoveden, Historia post Bedam.
i K. F. Eichhorn, Deutsche Staats und Rechtsgeschichte.
[j] Ciacconius (Chacon), Vitæ Pontificanum.
[k] J. C. L. Gieseler, Compendium of Ecclesiastical History (translated by J. W. Hull).
[l] Henry Hallam, The State of Europe during the Middle Ages.