Use databases to find academic articles to continue your research. Below are the most helpful databases for finding relevant articles on graphic design.
Note: If you are looking for collections or databases of images, take a look at the Finding Images guide (follow hyperlink or find the green tab to the left). This will take you to the Images guide. Once on the guide, click the "Image Databases" tab. The first box you will see, "Art Images Databases" contains links to collections of various high-quality/high-definition images from museums and galleries around the world.
Graphic Design Journals
The following are links to specific academic journals which are published and peer-reviewed by experts in the field. If you want to narrow your search to a specific time period or genre, finding a journal that publishes in that area can help.