Kajzer, Leszek. “Remarks on the Defending Constructions of the Gniezno Archbishops”. Acta Universitatis Lodziensis. Folia Archaeologica, no. 3 (January 1, 1983): 147–158. Accessed May 18, 2024. https://czasopisma.uni.lodz.pl/archaeo/article/view/16098.