Leo Lucassen is Professor of Social History at Leiden University. He is a member of the Academia Europaea and has published extensively on migration, integration, urban history and state formation. Wim Willems is Professor of Social History at Leiden University. He has created a stir with his autobiographical stories, including Stadskind. Kroniek van een naoorlogse jeugd (City Child. Chronicle of a Postwar Youth) and Stadsblues. Kroniek van de jaren zestig (City Blues. Chronicle of the Sixties).