As you are starting to explore a new research topic, reference sources are a good way to gain background information on your topic. High quality, academic, multivolume sets, will often give you the beginnings of scholarly research on a subject by providing a short bibliography of important works on the subject.
Even with advanced subject knowledge of an area, you will run across unfamiliar people, places and events. Library reference sources will allow you to quickly fill in those gaps and improve your contextual knowledge with more reliability than a Wikipedia article.
Here are the titles that were mentioned in class that will get you started in researching your image. For a paper of this length, you can find a great amount of information in reference sources. These are located in the reference section on the first floor of the library or online (to search all of the Grove titles together, go to this page, and use the "search within results" box on the left. Remember, you will be more likely to find information if you search for the topics that surround your image than if you search for your image specifically.