Europèaische Stammtafeln (Isenburg edition) @ chart 348, Alix de Courtenay, d of Pierre Capet & Elizabeth de Courtenay
The cited information was published by Verlag von J.A. Stargardt, Marburg, Germany, 1953, 1975 (Ref: chart 348, Alix de Courtenay, d of Pierre Capet & Elizabeth de Courtenay) The author/originator was Prince Wilhelm Karl von Isenburg.