lower right in plate: A; lower left in graphite by unknown hand: An Obscure Turning I; lower right verso in graphite by unknown hand: (c)
(Campbell Fine Art, Kent, England); Corcoran Gallery of Art, Washington, DC, 2004; acquired 2015 by the National Gallery of Art
- Hausberg, Meg. Clifford Addams: Etchings and Drypoints. London: N.W. Lott & H.J. Gerrish, 1984, no. 20.