Tolong jelaskan mengenai Catatan dari Markgrafschaft Geronis

Reuter, Timothy. Germany in the Early Middle Ages 800–1056. New York: Longman, 1991.

Thompson, James Westfall. Feudal Germany, Volume II. New York: Frederick Ungar Publishing Co., 1928.

Leyser, Karl. "Ottonian Government." The English Historical Review, Vol. 96, No. 381. (Oct., 1981), pp 721–753.

Leyser, Karl. "Henry I and the Beginnings of the Saxon Empire." The English Historical Review, Vol. 83, No. 326. (Jan., 1968), pp 1–32.

Lang, Henry Joseph. "The Fall of the Monarchy of Mieszko II, Lambert." Speculum, Vol. 49, No. 4. (Oct., 1974), pp 623–639.

Dvornik, F. "The First Wave of the Drang Nach Osten." Cambridge Historical Journal, Vol. 7, No. 3. (1943), pp 129–145.

Jakubowska, Bogna. "Salve Me Ex Ore Leonis." Artibus et Historiae, Vol. 12, No. 23. (1991), pp. 53–65.

Howorth, H. H. "The Spread of the Slaves. Part III. The Northern Serbs or Sorabians and the Obodriti." The Journal of the Anthropological Institute of Great Britain and Ireland, Vol. 9. (1880), pp 181–232.