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.

In his journal entry for May 27, 1961, Indiana notes making the final modifications on The Triumph of Tira, "moving [the] letters into red," and The Sweet Mystery, "recovering [the] stripes [to] black; likewise [the] letters (ivory)." Although he records that he is contemplating "no further changes on either; only additional touch up coats," later journal entries reveal that he did make changes.  Indiana also describes working on the painting Wombs (destroyed).

Indiana often referenced current events in his journals. Here he records that Nikita Khrushchev, premier of the Soviet Union, left Moscow for Vienna, where on June 4 he would meet John F. Kennedy, president of the United States, at the Vienna Summit.