Union List of Artists' Names (ULAN)
For alternate names and spellings
Thesaurus of Geographic Names (TGN)
For place names and their variants.
Heilbrunn Timeline of Art History. Metropolitan Museum of Art, NY
A chronological, geographical, and thematic exploration of the history of art illustrated by the Metropolitan Museum of Art's collection. Global coverage from prehistory to modern. Authored by the Met's curatorial, conservation and education staff.
Keyword searches are a good way to start, but subject searches can be more specific. To execute a subject search, choose "subject" from the drop-down menu in the catalog or a database. The Fashion Institute of Technology's Subject Guide for Art History & Fine Arts lists hundreds of subject terms appropriate for art historical research.
Subjects for Italian Renaissance art history include:
Specific media are also good subject words: painting, sculpture, altarpieces, bronze
When researching a work of art, try to begin with the website of the museum or institution that owns the work if possible. The musuem or institution can often provide important background information that will help you as you go deeper into the research. If researching an architectural work like a church, try to begin with the website of the entity that owns the site or a foundation dedicated to preserving the site.
Contextualize the work:
In addition to using museum websites, you can use a database like ARTstor to find high resolution images of the work, other works by the artist or architect, other works made during the same time and place, and other works on the same subject.