Stages of SIFT particular to artists:
Qualities of PATS particular to historians:
Museum websites = the one kind of website I can recommend without hesitation for research in art topics.
They often provide rich online access to images from their collections. Remember to cite appropriately any images you use in a presentation or paper.
We will also sometimes have books from major museum exhibits over the years.
If you are confused about whether you can use an image legally, consult The Public Domain, by Stephen Fishman.