Europèaische Stammtafeln (Isenburg edition) @ Band II Table 70, s of Olaf Bjornsson King of Sweden, no mother
The cited information was published by Verlag von J.A. Stargardt, Marburg, Germany, 1953, 1975 (Ref: Band II Table 70, s of Olaf Bjornsson King of Sweden, no mother) The author/originator was Prince Wilhelm Karl von Isenburg.