by Alfred Stieglitz, lower left, in graphite: Two Towers -- New York / 1911; lower right: Alfred Stieglitz 1911
by later hand, lower right, in graphite: 2; on backing board, center verso, on Alfred Stieglitz Collection label, in black ink: Alfred Stieglitz The Two Towers / New York, 1912 / Original Gravure / Proof / Stieglitz Exhibition, Photo-Secession / Gallery, 1913; center verso: An American Place stamp; center right verso: 1944 Philadelphia Museum of Art label
by later hand, lower left verso, in graphite: 139A
Georgia O'Keeffe; gift to NGA, 1949.
- Stieglitz Exhibition, Photo Secession Galleries, New York, 1913, no. 30, as Two Towers, New York, 1911
- Photo Secession Galleries, New York, 1915, no. 25, as The Two Towers, New York, 1912.
- History of an American: "291" and After, Philadelphia Museum of Art, Philadelphia, 1944, no. 25.
- Camera Work 44, October 1913, pl. 2 ("Two Towers -- New York").
- Greenough 2002, cat. 352.