P. Strzyż and J. Wrzosek, “(Review) Sven Ekdahl, In Search of the Battlefield of Tannenberg (Grunwald) of 1410. New Research with Metal Detectors in 2014–2019, Vilnius 2019, pp. 279. : On the Problems of Battlefield Research”, FAH, vol. 34, pp. 159–162, Dec. 2021.