Grasskamp, W. (2008). Gerhard Richter: An Angel Vanishes. Flash Art.
Lua i Stíl Chicago (17ú heag.)Grasskamp, Walter. "Gerhard Richter: An Angel Vanishes." Flash Art 2008.
Lua MLA (8ú heag.)Grasskamp, Walter. "Gerhard Richter: An Angel Vanishes." Flash Art, 2008.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.