Original title: "Berlins drittes Geschlecht: Schwule und Lesben um 1900" (Berlin's third gender: Gays and lesbians around 1900) by Magnus Hirschfeld. The book was published in 1904 and republished many times, including the editions of 1991 and 2015.
"Hirschfeld is still unmatched in the vividness and scope of gay and lesbian life in Berlin, although he, too, had to make concessions to public opinion and censorship; for example, he avoided more detailed place names.
The epilogue by Manfred Herzer deals with the history of publications on "Warm Berlin" dating back to the 18th century.
In an appendix, the psychiatrist Paul Näcke describes a "visit to the Homoseuxllen in Berlin", which he undertook under Hirschfeld's leadership and during which he saw some things differently than his companion."