Hanne Darboven, II-b, 1970–73, Ink and typewriting on twenty-eight pieces of paper, The Museum of Modern Art, New York. https://dartabase.art/cite/moma/36558

Hanne Darboven, 49 x 49 (7 x 7 = 49), 1972–73, Graphite pencil on 49 sheets of lined paper, The Museum of Modern Art, New York. https://dartabase.art/cite/moma/35852