In 1891, Bernstein was one of the authors of the Erfurt Program and from 1896 to 1898, he published a series of articles entitled "Probleme des Sozialismus" ("Problems of Socialism") that resulted in the revisionism debate in the SPD. He also published the book "Die Voraussetzungen des Sozialismus und die Aufgaben der Sozialdemokratie" ("The Prerequisites for Socialism and the Tasks of Social Democracy") in 1899. The book was in great contrast to the positions of Bebel, Kautsky and Liebknecht. Rosa Luxemburg's 1900 essay "Reform or Revolution?" was also a polemic against Bernstein's position. In 1900, Berstein published "Zur Geschichte und Theorie des Sozialismus" ("The History and Theory of Socialism").