Bella, Pavel, in Pavel Bosák. „Ceiling Erosion in Caves: Early Studies and Zdeněk Roth As Author of the Concept“. Acta Carsologica 44, no. 1 (julij 9, 2015). Pridobljeno julij 18, 2024. https://ojs.zrc-sazu.si/carsologica/article/view/768.