1999 Doctoral Thesis about "The Rights of Phonogram Producers in International Law" The thesis provides a broad overview on the legal rights of phonogram producers given by (1) the international treaties (2) in the field of the harmonisation of European copyright law and comparative (3) the German, the American, French and Japanese legal systems. 2002 "Copycontrol Systems for Audio-CDs - Can we claim a right for the Private Copy?" The article describes the actual economic problems of the recording industry facing losses in CD selling caused by massive private copying of music CDs on CD-ROMs and the attempts of the industry to stop this practice by introducing a copy control system. The paper analyses the legal situation under German and European copyright law.        "Exhaustion Online? The actual problems with On-Demand-Transmission of Phonograms under the new Copyright Directive concerning the Information Society" The article focuses on the problem of exhaustion in the field of the new On-Demand-Right. It analyses the provisions of the new Copyright Directive on the Information Society and the question whether  the provisions on exhaustion will be applicable in the context of On-Demand-Transmissions. GRUR Int. 2002, 414