companions from different phases of the development of CR, as well as current research colleagues from all over the world, have been invited to shed light on different aspects of Prof. Wallner’s oeuvre from several disciplinary and cultural perspectives. The nineteen contributors from Asia and Europe as well as North and South America explain and evaluate Wallner’s work and show the numerous fields of application and reveal possibilities for further development; not least by pointing out the one or other vagueness of CR as well as by referring to some overlaps with other schools of thought. In order to facilitate further discussions concerning CR, the appendix offers a selected bibliography to help readers find their way through the wide field of Friedrich, respectively Fritz (G.) Wallner’s publications.