Breznik, M., and L. Žlebnik. “Geologic Conditions Along the Drava River Between Maribor and Ptuj With Special Regard to the Construction of Water Power Plants”. Geologija, vol. 7, no. 1, June 1961, pp. 151-76, https://www.geologija-revija.si/index.php/geologija/article/view/1577.