Dormant, Abeyant, Forfeited, and Extinct Peerages @ p. 371, Montacute, Barons Montacute, Earls of Salisbury
The cited information was published by Burke's Peerage, Ltd., London, England, 1883, held in
{REPO232} (Ref: p. 371, Montacute, Barons Montacute, Earls of Salisbury) The author/originator was Sir Bernard Burke.
Dormant, Abeyant, Forfeited, and Extinct Peerages.