Complex sentence: However, that's according to the posthumous anonymous antisemitic 1923 source which credits Marsden as the translator in the pamphlet's preface, although Marsden had died three years earlier on October 28,1920.
Split into simpler sentences: However, that's according to the posthumous anonymous antisemitic 1923 source which credits Marsden as the translator in the pamphlet's preface. But it is to be noted that Marsden had died three years earlier on October 28,1920.