How can I reference a graph, table, figure or photograph I have found in a book, journal article or website?
You can treat graphs, tables, figures or photograph - basically any sort of drawing, figure or photograph in a text - as illustrations.
How you reference them depends on whether you have copied them into your text. See the examples in the lists.
The only exception to the above is where the illustration, photograph or figure is of a work of art - follow the separate instructions for illustrations of works of art in the Examples: A-B pages.