Graßhoff, Gerd Max Planck Fellow Computational History of Science, Max Planck Institute for the History of Science, Max Planck Society;
https://zenodo.org/record/3585774#.YIkxTWhCRTY (beliebiger Volltext)
Sum, J., Kotschka, F., & Graßhoff, G. (2019). Decoration of Ancient Sundials. Zenodo. doi:10.5281/zenodo.3585774.