Kurt Ostwald's Grosstadt-Dokumente: Hammer, Salten, Hirschfeld, Winter

Here is the German Wikipedia article which links to some of the scans of individual volumes in German libraries.

I wandered into this domain because of the Austrian journalist and city sociologist Max Winter.

In addition to Hirschfeld the sexologist, there are also the works of Hammer, who was interested as a doctor in collection biographies from the prostitutes he had controlled for sexually transmitted diseases.

• Band 23. Wilhelm Hammer: Zehn Lebensläufe Berliner Kontrollmädchen [1905], urn:nbn:de:kobv:109-1-6389955, digitalisiert von: Zentral- und Landesbibliothek Berlin, 2014.