Extensive international correspondence with various persons 1942-1983, including Achim von Borries, Boris Goldenberg, Pantelej Gumarov, Georg Hepp, Georg Kriesel, Andreas Mytze, Rose Pesotta, Max Piechula, Alfons Tomasz Pilarski, Otto Reimers, Eugen Relgis, Rudolf Rocker, Josef Stochloss, Peter Thoma, Ingeborg Weber, Alfred Weiland; with publishers and newspapers, universities and research centers, political parties, labour and/or anarchist organizations, broadcasting corporations, the International Institute of Social History (IISH), etc.; personal documents; typescripts of published and unpublished works by Souchy including his memoirs `Attention Anarchist!' and `Ideal und Wirklichkeit'; files on the International Labour Office (ILO), the Confederación Revolucionaria de Obreros y Campesinos (CROC), the War Resisters' International (WRI), the Föderation Freiheitlicher Sozialisten (FFS), the Sveriges Arbetares Centralorganisation (SAC), etc.; files concerning Buenaventura Durruti and Traven Torsvan; files on different countries visited by Souchy; documents on interviews with and lectures and book reviews by Souchy; collection of press clippings on the political and economic situation in countries all over the world; printed material.