Rudolph Ackermann, British Institution (Pall Mall) (detail), 1808.
Artists copying old masters. Source: Wikipedia
This guide is about European painters working in the fine art tradition, from the Middle Ages to the end of the eighteenth century. Many of the resources listed will also be useful for studying other media, other areas, and other time periods.
You may also want to run supplementary searches in these databases:
For introductory articles:
Some resources focussing on women artists: