Zimmermann, Reinhard MPI for Comparative and International Private Law, Max Planck Society;
Zimmermann, R. (2009). Principles of European Contract Law. In J. Basedow, K. J. Hopt, & R. Zimmermann (Eds.), Handwörterbuch des Europäischen Privatrechts (pp. 1177-1180). Tübingen: Mohr Siebeck.