At first glance, catalogs may look like just "coffee table books." However, they are key sources for art historical research. Here are several kinds of catalogs you may encounter.
Exhibition catalogs document time-limited exhibitions of material, which you might think of as public acts of scholarship. In addition to reproductions of items on display (and related reference images), these catalogs usually contain information-rich entries about those items, and longer, scholarly essays that explore themes brought out by the exhibition.
Catalogues raisonnés attempt to provide comprehensive documentation of an artist's work, or sometimes of an artist's work in a particular medium. Technical information and provenance history of individual items are usually covered, and disputed attributions and lost works frequently have their own section.
Museum catalogs cover the holdings of a particular institution.
You can find catalogs in Primo by adding the word "catalogs" to a search on an individual artist, movement, period, subject, etc.