These types of items are usually cited in the notes, not the bibliography.
Original Located in a Museum or Institution
General Notes Format:
Illustrator/Entity First Name Last Name, "Title of Item" (brief description), date, Name of Institution that Houses it, Location of Institution.
For Example:
Andrew Jackson Houston, "The Siege of Bexar" (map), ca. 1836, Texas State Library, Austin, TX.
Found in a Print Source
General Notes Format:
Illustrator/Entity First Name Last Name, "Title of Item" (brief description), date, in Author/Editor's First Name Last Name, Title of Book (Publication Place: Publisher, Publication Year), page number.
For Example:
George T. Long, "That Man From Wall Street" (advertisement), 1908, in Dwight Garner Read Me: A Century of Classic American Book Advertisements (New York: Harper Collins, 2009), 34.
Found Online
General Notes Format:
Illustrator/Entity First Name Last Name, "Title of Item" (brief description), date, NAme of Institution that Houses it or Website Name,Location of Institution, accessed date, URL address.
For Example:
Benjamin Franklin, "Join or Die" (political cartoon), 1754, Library of Congress, accessed April 28, 2016, http://www.loc.gov/pictures/resource/cph.3a12149/.