Art historical literature examines artists, artistic styles and movements, artistic practices, individual works of art, physical components of artworks and much more, and it also includes visual analysis and criticism. This interdisciplinary field uses theories and methodologies of its own, but often incorporates many other forms of analysis and criticism, such as feminism, gender studies, and political philosophies, to name just a few.
Keep in mind that research on individual artists or their works of art, and even contemporary art is included under the "art history" heading!
When researching in art history you will encounter a number of types of specialized art historical literature (see below). Bibliographies from any of these types of works can provide additional valuable resources.