Notes
The article has benefitted from the cooperation between the Rheinisch‐Westfaelisches Institut für Wirt‐schaftsforschung (RWI), Essen, the Institut für Arbeit und Technik (IAT), Gelsenkirchen, the Economics Ministry of North‐Rhine Westphalia, Ministerium für Wirtschaft, Mittelstand und Technologie (MWMT), Düsseldorf. The author owes special thanks to Dr. Roland Döhrn and Dr. Ullrich Heilemann (RWI), Wolfgang Potratz (IAT), and Alois Fischer and Dr. Reinhold Eisold (MWMT) for their precious support and preparatory work.