Above all, I would like to take the opportunity here to thank all of those who have extended their interest and attention for Roger Lips’ works, and have supported me with advice and suggestions.

My thanks also goes to the authors, whose contributions facilitate a good introduction to Lips’ work.

For the editorial assistance as well as translation and help and support with the realization of an Internet site I extend my heartiest thanks to Dr. Mathias Wallerang, Berlin, Linda A. Thomsen, Troisdorf and Angelika Wichert, Berlin.

Thanks also to the unknown Java-programmers, who enable the clearly arranged navigation.

My thanks also goes to Franz Bungter for his confidence and his complete and unreserved support.

Thomas Michalak, Berlin, December 1998.