Graßhoff, Gerd Max Planck Fellow Computational History of Science, Max Planck Institute for the History of Science, Max Planck Society;
http://repository.edition-topoi.org/collection/BSDP (beliebiger Volltext)
Graßhoff, G., Rinner, E., Schaldach, K., Fritsch, B., & Taub, L. (2016). Ancient Sundials (Database). doi:10.17171/1-1.