Sources

Archival sources:
Home Office papers: HO 40, 44 and 45 [The National Archives]
Hansard Parliamentary Papers [available online: https://api.parliament.uk/historic-hansard/index.html]
Police (Liverpool Inquiry) Act, 1909 [Liverpool Record Office]
Watch Committee Reports (Liverpool) [Liverpool Record Office]
Watch Committee Reports (Manchester) [Manchester Central Library]

National newspapers:
Annual Register 
The Observer 
The Times

Manchester newspapers:
Cowdroy's Manchester Gazette
Gorton Reporter
Manchester and Salford Advertiser
Manchester City News
Manchester Courier and Lancashire General Advertiser 
Manchester Evening Chronicle
Manchester Evening News 
Manchester Mercury 
Manchester Times
Wheeler's Manchester Chronicle

Liverpool newspapers:
Gore's Liverpool General Advertiser 
Liverpool Courier
Liverpool Courier and Commercial Advertiser 
Liverpool Daily Post
Liverpool Echo
Liverpool Evening Express 
Liverpool Mail
Liverpool Mercury 
Liverpool Weekly Albion

Glasgow newspapers:
Daily Record 
Evening Citizen 
Evening Times
Glasgow Chronicle 
Glasgow Courier 
Glasgow Echo
Glasgow Examiner 
Glasgow Free Press 
Glasgow Gazette 
Glasgow Herald 
Glasgow Sentinel 
Glasgow Weekly News 
North British Daily Mail 
Scottish Guardian Scotsman
Sunday Mail 
Sunday Post

Secondary sources:
Busteed, M. (2016). The Irish in Manchester c.1750-1921: Resistance, adaptation and identity (1 edition). Manchester: Manchester University Press.
Davies, A. (1998a). Street Gangs, Crime and Policing in Glasgow during the 1930s: The Case of the Beehive Boys. Social History, 23(3), 251–267.
Davies, A. (1998b). Youth Gangs, Masculinity and Violence in Late Victorian Manchester and Salford. Journal of Social History, 32(2), 349–369.
Davies, A. (2013). ’They Sing That Song’ : Football and Sectarianism in Glasgow during the 1920s and 1930s. In Bigotry, football and Scotland : perspectives and debates. Ed. Kelly, John; Flint, John (pp. 50–64). Edinburgh: Edinburgh University Press.
Herbert, M. (2001). The Wearing of the Green: A Political History of the Irish in Manchester. Irish in Britain Representation Group.
Jenkinson, J. (1987). The 1919 Race Riots in Britain. University of Edinburgh, Edinburgh.
Murdoch, N. H. (1992). Salvation Army Disturbances in Liverpool, England, 1879-1887. Journal of Social History, 25(3), 575–593.
Navickas, K. (2016). Protest and the Politics of Space and Place, 1789-1848. Manchester: Manchester University Press.
Neal, F. (1988). Sectarian Violence: The Liverpool Experience, 1819-1914. Manchester: Manchester University Press.
Neal, F. (1992). Bigots or Patriots? The Politcal and Religious Allegiances of the Liverpool Ships Carpenters 1815-1851. In Lewis R. Fischer (Ed.), From Wheel House to Counting House Essays in Maritime Business History in Honour of Professor Peter Neville Davies. Liverpool: Liverpool University Press. 
Stevenson, J. (1979). Popular Disturbances in England, 1700-1870. London: Longman Group.
Tiratelli, M. (2018). Rioting and time. PhD manuscript (University of Manchester).
Waller, P. J. (1981). Democracy and Sectarianism: Political and Social History of Liverpool, 1868-1939. Liverpool: Liverpool University Press.