Al-Malabeh, Ahmad, and Stephan Kempe. 2016. “Origin of Iron Ore Nuggets (‘Bohnerze’) through Weathering of Basalt As Documented by Pebbles from the Herbstlabyrinth, Breitscheid-Germany”. Acta Carsologica 34 (2). Ljubljana, Slovenija. https://doi.org/10.3986/ac.v34i2.271.