1. von Arnim, Hans Herbert, and Martin Schurig. 2004. The European Party Financing Regulation. Münster: LIT Verlag
2. Auel, Katrin, and Guido Tiemann. 2020. Europeanising European Public Spheres. Brussels: European Parliament.
3. Bardi, Luciano, Edoardo Bressanelli, Enrico Calossi, Wojciech Gagatek, Peter Mair, and Eugenio Pizzimenti. 2010. How to Create a Transnational Party System. Brussels: European Parliament.
4. Bardi, Luciano et al. 2014. Political Parties and Political Foundations at European Level: Challenges and Opportunities. Brussels: European Parliament.
5. Braun, Daniela, and Sebastian Popa. 2018. This Time It Was Different? The Salience of the Spitzenkandidaten System Among European Parties. West European Politics 41 (5): 1125–1145.