See Louis Ginzberg. “Eine unbekannte judische Sekte,” originally published in Monatsschrift für die Geschichte und Wissenschaft des Judentums 55–58 (1911–1914), and later privately published as a book in 1922. Ginzberg expected to publish additional material, but when World War II came he forswore publishing in German. As a result, only with the appearance of the English edition, An Unknown Jewish Sect (New York: Jewish Theological Seminary, 1976), was his full study published.