* [http://www.muellerscience.com/SPEZIALITAETEN/System/System_Definitionen.htm ''Definitionen von "System" (1572–2002)''] by Roland Müller, (most in German). | * [http://www.muellerscience.com/SPEZIALITAETEN/System/System_Definitionen.htm ''Definitionen von "System" (1572–2002)''] by Roland Müller, (most in German). |