Complex sentence: Professor Kolb has published outstanding books on Imperial Germany, the Weimar Republic, and the Third Reich, and his learned summary of research on the Weimar Republic is mandatory reading for all students of modern German history.
Split into simpler sentences: Professor Kolb has published outstanding books on Imperial Germany, the Weimar Republic, and the Third Reich. His learned summary of research on the Weimar Republic is mandatory reading for all students of modern German history.