In addition to numerous articles and essays, his works include:
The Banks and the Steel Industry in the Ruhr: Developments in Relations from 1874 to 1914 (1981)His article, "Big Business in Interwar Germany: Organizational Innovation at Vereinigte Stahlwerke, IG Farben, and Siemens," in the Autumn 1987 Business History Review won the Newcomen Prize for the best essay in the BHR that year.
Werner von Siemens: Inventor and International Entrepreneur (1994)
Siemens, 1918-1945 (1999)
Siemens: From Workshop to Global Player (2000)
"Vom Guten das Beste": Von Daimler und Benz zur DaimlerChrysler AG (2003)
Die Siemens-Unternehmer (2005)
A fuller CV may be found here, and obituaries here and here. A video of Professor Feldenkirchen inspecting and discussing the Victoria (in German; audio begins c. 2 min. in) is available on YouTube.