sentences:  His earliest portraits of his mother, in which he experimented with a variety of styles including that of Vuillard and late Cubism, date back to when he was just 16 years old.He continued his artistic training at the Kunstgewerbeschule in Vienna (1911–13) and later at the Munich Academy of Fine Art under Angelo Jank (1913–14).It was during this period that he was exposed to European Expressionist masters, falling under the influence of expressionists like Max Beckmann and Egon Schiele.