1.
Siman M. Equality Through Differentiation: Opt-Outs and Enhanced Cooperation as Expressions of Sovereignty. In: Author T, Author T, eds. Unequal Equals? The Status of Member States in an Integrating European Union. Studies of the Central European Professors’ Network; 2026:235–277. doi:10.54237/profnet.2026.dsuesmsieu_7