The Carolingian era refers to works set under the Frankish dynasty that reigned in France a.d. 751–987, firstly under Charlemagne, and in Germany until a.d. 911.

The Carolingian World
Carolingian Culture: Emulation and Innovation
Carolingian Civilization: A Reader
Charlemagne: The Formation of a European Identity
Charlemagne's Courtier: The Complete Einhard (Readings in Medieval Civilizations & Cultures #3)
The Frankish Kingdoms Under the Carolingians 751-987
Carolingian Portraits: A Study in the Ninth Century
History and Memory in the Carolingian World
In the Manner of the Franks: Hunting, Kingship, and Masculinity in Early Medieval Europe
Struggle for Empire: Kingship and Conflict Under Louis the German, 817-876
SON OF CHARLEMAGNE. A contemporary life of Louis the Pious
Benedict Of Aniane: The Emperor's Monk
Charlemagne's Cousins: Contemporary Lives of Adalard and Wala
Emperor Of The West: Charlemagne And The Carolingian Empire