Lineage & Ancestry of HRH Prince Charles, Prince of Wales @ Vol I p 70, Rainou de Sabran --Seigneur d'Castellan, Count Forcalquier
The cited information was published by Skilton, Edinburgh, Scotland, 1977 (Ref: Vol I p 70, Rainou de Sabran --Seigneur d'Castellan, Count Forcalquier) The author/originator was Gerald Paget.