lower right, on stone: IV-'56 / MCE; lower left, in pencil: MCEscher No. 16/40
- "M. C. Escher", National Gallery of Art, Washington, DC, 1974.
- Bool, F.H. et al. M.C. Escher: His Life and Complete Graphic Work. Amsterdam: Meulenhoff, 1981; English-language edition, New York: Harry N. Abrams, 1982.