sentences:  Furthermore, he was active in London as a correspondent for several radical Russian newspapers.Rothstein also wrote articles for "Die Neue Zeit", the organ of the Social Democratic Party of Germany (SPD), which represented the direct way of a consistent Marxism and in which took place debates regarding Marxism and socialism.In 1895, he joined the Social Democratic Federation (SDF) which was founded by H.M. Hyndman in 1884.