The producers wish to thank:

• Max Duenki for his technical support.
• Hanspeter Schmid for his explanations of how to scan properly.
• Martin von Stein and Roya Soleymani Kohler for providing access to the scanner of the EE department.
• Gerhard Kraemer and Beat Keusch for their moral support and for their promise to participate in the production of the next draft version.