Butler, D. E., & Freeman, J. (1969). British political facts, 1900-1968 ([3d ed.].). Macmillan.
Lua i Stíl Chicago (17ú heag.)Butler, David E., agus Jennie Freeman. British Political Facts, 1900-1968. [3d ed.]. London: Macmillan, 1969.
Lua MLA (9ú heag.)Butler, David E., agus Jennie Freeman. British Political Facts, 1900-1968. [3d ed.]. Macmillan, 1969.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.