Terry Clavin: Butler, Lady Margaret. In: Royal Irish Academy (Hrsg.): Dictionary of Irish Biography. Cambridge University Press (cambridge.org).
doi.org
Mary Ann Lyons: Butler [née Fitzgerald], Margaret, countess of Ossory and Ormond. In: Oxford Dictionary of National Biography. doi:10.1093/ref:odnb/69168.
Eleanor Hull: A History of Ireland and her People. George G. Harrap & Company Ltd., London 1926, IX. The Geraldines: The House of Desmond and the House of Kildare, S.261–285 (hathitrust.org).