Piech, W. 2018. Assessment of natural environment of the early medieval stronghold at Rękoraj in the Piotrków Upland, Central Poland. Acta Universitatis Lodziensis. Folia Geographica Physica. 16 (Mar. 2018), [33]-42. DOI:https://doi.org/10.18778/1427-9711.16.04.