Clive Bean (2009). «New Zealand». En Mark N. Franklin; Thomas T. Mackie; Henry Valen, eds. Electoral Change: Responses to Evolving Social and Attitudinal Structures in Western Countries. ECPR Press. p. 285. ISBN978-0-9558203-1-1.
Papillon, Martin; Turgeon, Luc; Wallner, Jennifer; White, Stephen (2014). Comparing Canada: Methods and Perspectives on Canadian Politics. UBC Press. p. 126. ISBN9780774827867. Consultado el 30 de agosto de 2016. «[...] [I]n New Zealand politics, by the centre-left Labour Party and the centre-right National Party [...].»