Complex sentence: He then travelled abroad, studying in Dublin, Vienna, Paris and Berlin, studying dermatology in Vienna under Ferdinand von Hebra and Moriz Kaposi, and in Paris under Jean Baptiste Emile Vidal and Jean Alfred Fournier.
Split into simpler sentences: He then travelled abroad, studying in Dublin, Vienna, Paris and Berlin. He studying dermatology in Vienna under Ferdinand von Hebra and Moriz Kaposi, and in Paris under Jean Baptiste Emile Vidal and Jean Alfred Fournier.