Kleinschmidt, Jens MPI for Comparative and International Private Law, Max Planck Society;
https://max-eup2012.mpipriv.de/index.php/Contractual_Terms,_Subsequent_Determination (Any fulltext)
Kleinschmidt, J. (2012). Contractual Terms. In J. Basedow, K. J. Hopt, & R. Zimmermann (Eds.), The Max Planck Encyclopedia of European Private Law (pp. 396-401). Oxford: Oxford University Press.