Europèaische Stammtafeln (Isenburg edition) @ Vol 2 chart 76, d of Guillaume VIII (Guido) Duc de Aquitaine, no mother
The cited information was published by Verlag von J.A. Stargardt, Marburg, Germany, 1953, 1975 (Ref: Vol 2 chart 76, d of Guillaume VIII (Guido) Duc de Aquitaine, no mother) The author/originator was Prince Wilhelm Karl von Isenburg.