Raap, J. (2004). Robert Crumb: "Yeah, but is it Art? ; Drawings and Comics ; Museum Ludwig Köln, 28.5.-12.9.2004. Kunstforum.
Citazione stile Chigago Style (17a edizione)Raap, Jürgen. "Robert Crumb: "Yeah, but Is It Art? ; Drawings and Comics ; Museum Ludwig Köln, 28.5.-12.9.2004." Kunstforum 2004.
Citatione MLA (8a ed.)Raap, Jürgen. "Robert Crumb: "Yeah, but Is It Art? ; Drawings and Comics ; Museum Ludwig Köln, 28.5.-12.9.2004." Kunstforum, 2004.
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