Roy Douglas, Liberals : A History of the Liberal and Liberal Democrat Parties, Hambledon Continuum, , 395 p. (ISBN1-85285-353-0, lire en ligne), « Politics in Chaos », p. 197
(en) Varian, « The growth of manufacturing protection in 1920s Britain », Scottish Journal of Political Economy, vol. 0, (ISSN1467-9485, DOI10.1111/sjpe.12223)
(en) Varian, « The growth of manufacturing protection in 1920s Britain », Scottish Journal of Political Economy, vol. 0, (ISSN1467-9485, DOI10.1111/sjpe.12223)