Heckmann, FriedrichFriedrichHeckmann2019-09-192015-07-131999https://fis.uni-bamberg.de/handle/uniba/38211engCitizenship and nation in Germany: old and new conceptsworkingpaperhttps://web.archive.org/web/20040518081406/http://www.uni-bamberg.de/~ba6ef3/pdf/efms_p32.pdf