HENNING, Joachim, Todor BALABANOV,
Peter MILO a Daniel ZIEMANN. Khan Omurtag´s stone palace of AD 822: a modernized eighth century timber fort. In
Post-Roman Towns, Trade and Settlement in Europe and Byzantium, Vol. 2: Byzantium, Pliska and the Balkans, Edited by Joachim Henning. Berlin - New York: Walter de Gruyter GmbH & Co. KG, 2007, s. 434-440, 8 s. ISBN 978-3-11-018358-0.