This refers to books, magazine, or journal articles you utilized in a printed or paper format.
This refers to books, magazine, or journal articles you utilized in an electronic format.
This refers to images found in either printed or electronic formats.
Advice from Bedford/St. Martin's Research & Documentation Online (5th edition) regarding how to cite works of art in the Chicago style:
Work of art: For an original work, give the artist, the title (italicized), the medium, the date of composition, and the institution or collection housing the work. To cite a reproduction, omit the medium and location and give publication information for the source.
Aaron Siskind, Untitled (The Most Crowded Block), gelatin silver print, 1939, Kemper Museum of Contemporary Art, Kansas City, MO.
Siskind, Aaron. Untitled (The Most Crowded Block). Gelatin silver print, 1939. Kemper Museum of Contemporary Art, Kansas City, MO.
Edward Hopper, August in the City, in Edward Hopper: The Art and the Artist, by Gail Levin (New York: Whitney Museum of American Art, 1980), 197.
Hopper, Edward. August in the City. In Edward Hopper: The Art and the Artist, by Gail Levin, 197. New York: Whitney Museum of American Art, 1980.