He also wrote a number of books on composition, and was a highly respected painter in the Expressionist school.<ref>Norbert Wolf, Uta Grosnick, ''Expressionism,'' 2004</ref> | He also wrote a number of books on composition, and was a highly respected painter in the Expressionist school.<ref>Norbert Wolf, Uta Grosnick, ''Expressionism,'' 2004</ref> |