Europèaische Stammtafeln (Isenburg edition) @ Band II table 70, d of Harald VII Bluetooth, K of Denmark, no mother
The cited information was published by Verlag von J.A. Stargardt, Marburg, Germany, 1953, 1975 (Ref: Band II table 70, d of Harald VII Bluetooth, K of Denmark, no mother) The author/originator was Prince Wilhelm Karl von Isenburg.