For overview articles on an artist or artistic movement your topic is part of, search in one of the recommended Reference Resources. These are usually short and often have a bibliography or further reading section where you can get titles of books and articles that are more in-depth.
Books are longer publications on one aspect of a topic. They may also include topic overviews, particularly in the introduction, preface and the conclusion sections, explaining how this aspect fits into a broader understanding.
Journal articles are shorter publications on very specialized aspects of a topic. They can be peer-reviewed and edited more quickly than books and thus may have the most current information.
A primary source reports what the author experienced directly. Common primary sources for art history include exhibition reviews; chemical analyses of paintings, papers, and sculptures; infrared and x-ray analyses; and interviews with an artist.
Images of an artwork are considered primary sources if they were made directly from the work, such as a photograph of a painting, digital images of an object, or a sketch of a building. On this guide are many sources for images, including open-access images from museums and galleries.