Knut Heidar & Ruud Koole 
Parliamentary Party Groups in European Democracies [PDF ebook] 
Political Parties Behind Closed Doors

The partisan groups in parliament form the link between mass suffrage, parties and parliaments, and are generally accepted today as necessary instruments of parliamentary business. Parliamentary party groups are central actors in most European democracies. This volume analyses the manifestations and operations of these actors across thirteen different countries and in the European parliament.