From International Signal Code Alphabet
Medium: Ink on paper with collage Dimensions: Sheet: 8 1/2 x 11 in. (21.6 x 27.9 cm) Credit Line: Collection UCLA Grunwald Center for the Graphic Arts, Hammer Museum. Corita Kent Bequest. Accession No.: 1990.1.1165 Paper/Support: Paper Inscriptions: u.r. handwritten in ink: "26"; l.r. handwritten in ink: "put this y in the lower right corner in red (instead of the one already there [sic]"; l.l. handwritten in ink: "these words will be yellow in the red stripes"
"Untitled." Corita Kent in the Grunwald Center Collection. Los Angeles: Hammer Museum, 2017. https://hammer.ucla.edu/collections/grunwald-center-collection/corita-kent/art/untitled-preparatory-material-for-y-is-for-why-not/.