List of corrections:

• Avar Khaganate was disestablished c. 803;
• Bulgarian-Frankish border was at the river Tizsa (Theiss) (see S. Rucniman, History of the First Bulgarian Empire);
• north-eastern border of Bulgaria beyond the Danube delta (see R. Crampton, A Concise History of Bulgaria, Cambridge UP, 2006);
• Serdica (Sofia) was part of the First Bulgarian Empire by the 814 peace treaty between the Bulgarians and Byzantines (see Cambridge Medieval History, vol. 4 (1923) and R. Crampton, loc. cit.)
• Kingdom of Galicia, not Asturias (see The New Penguin Atlas of Medieval History, 1992, 42-45, and Das Mittelalter: Streifzug durch eine Epoche, National Geographic Deutschland, jan. 2015, 57)
• Croatian, Serbian, Paganian, Zachlumian, Travunian, Dioclean borders (see N. Budak, Hrvatska Povijest od 550. do 1100., 2018; T. Živković, On the northern borders of Serbia in the early middle ages, 2001; S. Ćirković, The Serbs, 2004; P. Komatina, On the Serbian-Bulgarian border in the 9th and the 10th centuries, 2015 etc.)
• Bosnian (N. Budak 2018; Tibor Živković, On the Beginnings of Bosnia in the Middle Ages, 2010; Muhamed Hadžijahić, Povijest Bosne u IX i X stoljeću, 2004; Relja Novaković, Where was Serbia from the 7th to the 12th century: Conclusion and summary of the monograph, 1981-2010; etc.)