He regarded educational reformer Gustav Wyneken (1875-1964) an early influence in his career, and was a member of several liberal and "youth culture" organizations.
Siegfried Line | Siegfried & Roy | Siegfried | Siegfried (opera) | Siegfried Wagner | Siegfried Matthus | Siegfried Lenz | Siegfried Palm | Siegfried II of Westerburg | Siegfried von Feuchtwangen | Siegfried Kasche | Siegfried, Count of Merseburg | Siegfried Bernfeld | ''Siegfried'' | Chris Siegfried | Bernhard Siegfried Albinus | Wolf pack Siegfried | Siegfried Verbeke | Siegfried Tiefensee | Siegfried Strelow | Siegfried Selberherr | Siegfried Saloman | Siegfried Reiprich | Siegfried of Luxembourg | Siegfried of Isenburg-Kempenich | ''Siegfried Map'' of the Türlersee | Siegfried Lenz. | Siegfried Köhler | Siegfried III | Siegfried Idyll |
Ernst Simmel, Hanns Sachs, Franz Alexander, Sándor Radó, Karen Horney, Siegfried Bernfeld, Otto Fenichel, Theodor Reik, Wilhelm Reich and Melanie Klein were among the many psychoanalysts who worked at the Institute.