ca. 3000 BC. Tomb O of F. Petrie
See:
- W. M. Flinders Petrie: The Royal Tombs of the Earliest Dynasties, 1901, Part II, London 1901, pl. XXVII, 96
- Bruce Trigger, Ancient Egypt: A Social History. Cambridge University Pres, 1983, p. 70
- http://www.phouka.com/pharaoh/pharaoh/dynasties/dyn01/02djer.html