lower left in graphite: 49/100; lower right in graphite: Sigmar Polke; lower left verso in graphite: P13 b
- Art for the Nation: Gifts in Honor of the 50th Anniversary of the National Gallery of Art. Exh. cat. National Gallery of Art, Washington, 1991: p. 444
- Paoletti, J., PCN, May-June 1991, #17.