Charlemagne: Biography of the emperor covering his political, military, and religious entanglements.
Charlemagne (Charles the Great): Biographical article on the Frankish ruler, in the 1911 Encyclopædia Britannica. With bibliography.
Legends of Charlemagne: A collection of early histories of Charlemagne.
The Life of Charlemagne: By Einhard. English translation by Samuel Epes Turner.
The Life of Charlemagne: By the Monk of St. Gall, thought by many to be Notker Balbulus.