The Modern Art Museum of Fort Worth - Donald Judd's "Untitled," 1967, in the Modern's collection, is part of a series known as "stacks," all composed of identical units stacked vertically and
Donald Judd, Untitled (Stack), 1967 | 3D Warehouse
Donald Judd: 'Stacks' - The New York Times
The First Donald Judd Retrospective in 32 Years Is Open Now at MoMA | Vogue
Minimalism Maxed Out - F Newsmagazine
Donald Judd. Untitled (Stack). 1967 | MoMA | Donald judd, Moma, Untitled