Robert Indiana kept a series of illustrated journals during the late 1950s and 1960s, in which he discusses the development of his work as well as his daily life on Coenties Slip. 

Indiana's journal page for February 6, 1962, consists of a sketch of the painting Polygon: Heptagon. To the right of the painting are two notes, "Pace Gallery" and "Riegelhaupts Boston, Mass." The painting was included in a December 1962 show at Pace Gallery, Stock Up for the Holidays: An Anthology of Pop Art, and was purchased by Elmer and Barbara Rigelhaupt of Boston. The note at the top of the page, "Anderson's invitation," refers to gallerist David Anderson. Indiana was part of a two-man show at the David Anderson Gallery in April 1961 (Indiana / Forakis), and the gallery sold three of his works, Moon (1960), The American Dream, I (1960–61), and Law (1960–62), all in the collection of the Museum of Modern Art, New York.