stamped into side of one metal component: MdS R © [chop of Gemini G.E.L.] 1381 34/50
- The Art of Collaboration: Works from the National Gallery of Art's Gemini G.E.L. Archive, Academy Art Museum, Easton, Maryland, 9 Dec 2006 - 3 Feb 2007.
- Gemini G.E.L. Catalogue Raisonné, no. 934.
- Fine, Ruth E. Gemini G.E.L.: Art and Collaboration. Washington, DC: National Gallery of Art, 1984, no. 94.
- Sculpture: An Illustrated Catalogue. National Gallery of Art, Washington, 1994: 78, repro.