Martens, Sebastian A.E. MPI for Comparative and International Private Law, Max Planck Society;
https://max-eup2012.mpipriv.de/index.php/Duress (beliebiger Volltext)
Martens, S. A. (2012). Duress. In J. Basedow, K. J. Hopt, & R. Zimmermann (Eds.), The Max Planck Encyclopedia of European Private Law (pp. 505-508). Oxford: Oxford University Press.