"Born in Neuwaldegg, Austria 1865, died in Amsterdam 1944; anarchist historian, collector and scholar; studied philology and Celtic (dissertation `Beiträge zur cymrischen Grammatik’, 1887); lived partly in Vienna, partly in London and travelled all over Europe to collect and to save historical documents on anarchism and socialism and for his studies; member of the Socialist League 1885-1890, active in the Torch and Freedom group; wrote historical works on anarchism with invaluable information and theoretical studies; printed by autocopyist his biography of Michail Bakunin, 3 vols. 1896-1900, and published `Bibliographie de l’anarchie’ 1897; lost during the inflation after the First World War the money he had inherited, and lived in poverty in Vienna; continued to collect and to publish e.g. biographies of Errico Malatesta and Elisée Reclus, and a history of anarchism in 7 vols.; sold his immense collection (books, periodicals, archives, documents) to the International Institute of Social History (IISH) in 1935 and lived in Amsterdam after the `Anschluss’. "
By the International Institute of Social History, Amsterdam (Holland)