Hendrickx, S., Arguments for an Upper Egyptian Origin of the Palace-Facade and the Serekh during Late ..., GM 184,

2001,85-110

Hoffman, M.,  Egypt before the Pharaohs, New York 1979

Kaiser, W., Einige Bemerkungen zur ägyptischen Frühzeit, ZÄS 91, 1964, 86-125

 -  Zur Entstehung des gesamtägyptischen Staates, MDAIK 46, 1990, 287-299

Midant-Reynes, B.,  Préhistoire de l'Egypte, Paris 1992

Spencer, A.J. (ed.), Aspects of Early Egypt, London 1996

van den Brink ed., The Nile Delta in Transition, Tel Aviv 1992

Vercoutter, J., L'Egypte et la vallée du Nil, vol. I, Paris 1992

Vinci, S.,  La Nascita dello stato nell' Antico Egitto: La Dinastia "Zero", Bologna 2002

Wilkinson, T.A.H., Early Dynastic Egypt, London/New York 1999

 - Political Unification: towards a reconstruction, MDAIK 56, 2000, 377-395.