Verboven, K. and C. Laes (2016). Work, labor and professions in the Roman World. Impact of Empire 23. Leiden.
Hekster, O. and T. Kaizer (2011). Frontiers in the Roman World. Proceedings of the Ninth Workshop of the International Network Impact of Empire (Durham, 16?19 April 2009). Impact of Empire 13. Leiden.
Hekster, O. and G. De Kleijn (2007). Crises and the Roman Empire: proceedings of the seventh workshop of the international network impact of Empire (Nijmegen, June 20-24, 2006). Impact of Empire. Leiden.