Siman, M. (2026). Equality Through Differentiation: Opt-Outs and Enhanced Cooperation as Expressions of Sovereignty. In D. Sehnálek (Ed.), Unequal Equals? The Status of Member States in an Integrating European Union (pp. 235–277). Studies of the Central European Professors’ Network. https://doi.org/10.54237/profnet.2026.dsuesmsieu_7