Firma del filósofo y escritor marxista Karl Kautsky.
https://www.foldvaribooks.com/pages/books/1717/karl-liebknecht-mano-buchinger-clara-zetkin-karl-kautsky/postcard-signed-by-early-prominent-socialists-at-the-sozialdemokratische-parteitag-jena-1913
Karl Kautsky