quoted Ulrichs's writings in the first psychiatric paper on 'contrary sexual feeling' and largely used Ulrichs's theoretical framework. Ulrichs also corresponded for many years with psychiatrist Richard von Krafft-Ebing, who later acknowledged his debt to Ulrichs, stating that it was "only the knowledge of your books which motivated me to study this highly important area".

Richard von Krafft-Ebing was a German psychiatrist and author of the foundational work Psychopathia Sexualis