{"The Plantagenet Ancestry," W.H.Turton (Balt.: Gen.Pub.Co., 1968) identifies Agatha "of Germany" as dau. of Bruno of Germany, Bishop of Augsburg and brother of Emperor Henry II. Ernest-Friedrich Kraentzler, "The Ancestry of Richard Plantagenet and Cecily de Neville," p. 58, states that Agatha is daughter of Ludolph von Braunschweig, Count im Derlingo, Marquis von Westfriesland, b. 1008, d. 04-23-1038, m, 1020 Gertrude von Egisheim. See Szabolcs de Vajay, "Agatha, Mother of St. Margaret, Queen of Scotland," in Duquesne Review, vol. 7, no. 2, Spring, 1962, pp. 71-80, with tables.}

References: [Isenburg],[Moriarty],[Weis1],[AR7]