* Feldenkirchen, Wilfried / Eberhard Posner (2005): "The Siemens Entrepreneurs", Continuity and Change, 1847–2005, Ten Portraits, Munich.
* Feldenkirchen, Wilfried / Eberhard Posner (2005): "The Siemens Entrepreneurs", Continuity and Change, 1847–2005, Ten Portraits, Munich.