upper left in graphite: 19" x 24 3/4" / Rag; upper center in graphite: one sun II / The Photon Structure; lower right in graphite: 4-2-73 / Rockne Krebs ©
Corcoran Gallery of Art, Washington, DC, 1974; acquired 2015 by the National Gallery of Art
- Simmons, Linda Crocker and with the assistance of Adrianne J. Humphrey, et al. American Drawings, Watercolors, Pastels, and Collages in the Collection of the Corcoran Gallery of Art. Washington, DC: Corcoran Gallery of Art, 1983: p. 255, no. 1684.