Evans, A.M. and M. Vink (2012). Measuring Group Switching in the European Parliament: Methodology, Data and Trends (1979–2009). Análise Social (页面存档备份,存于互联网档案馆), XLVII (202), 92–112. See also McElroy, G. (2008), "Intra-Party politics at the trans-national level: Party switching in the European Parliament". In D. Giannetti and K. Benoit (eds.), Intra-Party Politics and Coalition Governments in Parliamentary Democracies, London, Routledge, pp. 205–226.
Evans, A.M. and M. Vink (2012). Measuring Group Switching in the European Parliament: Methodology, Data and Trends (1979–2009). Análise Social (页面存档备份,存于互联网档案馆), XLVII (202), 92–112. See also McElroy, G. (2008), "Intra-Party politics at the trans-national level: Party switching in the European Parliament". In D. Giannetti and K. Benoit (eds.), Intra-Party Politics and Coalition Governments in Parliamentary Democracies, London, Routledge, pp. 205–226.