Flam, J., Rogers, K., Clifford, T., 2012. Robert Motherwell Paintings and Collages: A Catalogue Raisonné 1941–1991: New Haven, Yale University Press. Vol. 3, Page 578, Pl. W478; Ratcliff, C, "New York Letter" Art International 10, nos. 3-4 (March - April 1976): p. 75.
Artist's Studio Number D75-319
Motherwell also assigned the number 12 to another work in the Gesture Paper Painting series (see W479)