lower left in graphite: No. 22/XL; lower right in graphite: Drewes - 74.; across bottom in graphite: To Ruth + Jacob in friendship, Werner; (by unknown hand) #330 INTRUSION
Ruth Kainen, Washington, DC; gift 2005 to NGA.
- Rose, Ingrid. Werner Drewes, A Catalogue Raisonné of his Prints. Munich and New York: Verlag Kunstgalerie Esslingen, c. 1984, vol. III, 389.