Hopt, Klaus J. MPI for Comparative and International Private Law, Max Planck Society;
https://max-eup2012.mpipriv.de/index.php/Private_Rule-Making_and_Codes_of_Conduct (Any fulltext)
Hopt, K. J. (2012). Private Rule-Making and Codes of Conduct. In J. Basedow, K. J. Hopt, & R. Zimmermann (Eds.), The Max Planck Encyclopedia of European Private Law (pp. 1348-1352). Oxford: Oxford University Press.