Sperr, Anneken Kari MPI for Comparative and International Private Law, Max Planck Society;
https://hwb-eup2009.mpipriv.de/index.php/Ombudsmann (Any fulltext)
Sperr, A. K. (2009). Ombudsmann. In J. Basedow, K. J. Hopt, & R. Zimmermann (Eds.), Handwörterbuch des Europäischen Privatrechts (pp. 1121-1126). Tübingen: Mohr Siebeck.