Strzelczyk, J. (1992). Review: Johannes Fried, Otto III. and Boleslaw Chrobry of the Aachen Gospels, the "Act of Gniezno" and the early Polish and Hungarian kingship. An image analysis and its historical consequences (Frankfurt Historical Treatises, Vol. 30), Stuttgart 1988. Our Past, 77, 307–315. https://doi.org/10.52204/np.1992.77.307-315