A graph can be a useful addition to any research paper, as it provides a visual reference to the point you are trying to convey. Graphs are generally used to display data in an interesting and easy-to-read manner. As with any other piece of research, cite a graph properly per American Psychological Association rules.
The manner in which you cite a graph depends on the type of source. The two most common sources are books and websites. When citing a graph from a book on the reference page, use this format: Author. (Publication Date). Title of graph, chart, or table [graph]. In author or editor of work, Title of work. Place of Publication: Publisher.
If the graph was found online, cite it like this: Author. (Publication Date). Title of graph, chart, or table [graph]. Title of website. Available/Retrieved from URL. Italicize either the title of the book or website. If your graph does not have a title, replace this section with a brief description of the item, and place this inside brackets.
When citing a graph in the text, place the citation in the body of your paper directly under the graph. For example, cite a graph found in a book as follows: Note. From Name of Book (in italics) p. number, by Author, Year, Publishing Information.
List a journal citation as: Note. From "Article name" by Author, Year, Journal Name (italics), Volume number (italics)(Issue number), p. number.