Burke's Genealogical History of the Dormant, Abeyant, Forfeited @ named as "Berta" only
The cited information was published by Burke's Peerage, London, 1866 (Ref: named as "Berta" only) The author/originator was Burke's Peerage.
Source Notes
TITL Burke's Genealogical History of the Dormant, Abeyant, Forfeited
& Extinct Peerages of the British EmpireABBR Burke's Dormant Peerage