Dunboyne 1968, pp. 16–17. "Butler Family Tree condensed" Dunboyne, Patrick Theobald Tower Butler, Baron (1968). Butler Family History (2nd ed.). Kilkenny: Rothe House.{{cite book}}: CS1 maint: multiple names: authors list (link)
Shaw 1906, p. 94. "1597-9, Jan. 22. Walter Butler, son and heir to John Butler, ... in St. Patrick's Church by Adam Loftus, archybishop of Dublin, and Sir Robert Gardiner ..." Shaw, William A. (1906). The Knights of England. Vol. II. London: Sherratt & Hughes. – Knights bachelors & Index
Armstrong 2009, 1st paragraph. "He served with his uncle in the later stages of the nine years war ..." Armstrong, Robert (October 2009). McGuire, James; Quinn, James (eds.). "Butler, Thomas". Dictionary of Irish Biography. Retrieved 28 August 2022.