Compositie van lijnen (1919) by Erich Wichmann, De Volharding B V and De Hooge Brug https://www.rawpixel.com/image/13763682/image-background-paper-frameFree Image from public domain licenseHeer en knecht (1927) by Erich Wichmann and Erich Wichmann https://www.rawpixel.com/image/13774298/heer-knecht-1927-erich-wichmann-and-erich-wichmannFree Image from public domain licenseVijf figuren op de Dag van de Arbeid (1923) by Erich Wichmann https://www.rawpixel.com/image/13766867/vijf-figuren-dag-van-arbeid-1923-erich-wichmannFree Image from public domain license