Since a majority of your information must come from printed text, you are going to have to visit a library at least once. To save yourself time, search the catalogs to see what is available before you go. Write down the title and call #s. It will save hours if you do this before you go to the Library. Don’t be afraid to ask for help while there--it's an ulterior motive of mine to actually get you to a college library before you, um, go to college. In fact, if you go to MASS Art Library, they will be expecting you!
Your Best Bet for Art Research:
Mass College of Art (Green Line, E train near Northeastern & MFA)
Boston Public Library (Green Line, Copley Square)
I have also had students go to the Museum of Fine Arts, Boston and be let into the special archives room.
Or Google any other college library and browse its online catalog before making the trip. You can call them and see their policies. Most are open to the public (except Harvard) but you will probably not be able to check out books.
Some good Art Magazines with websites.
Libraries will often have these archived. But you can see which issues, if any, relate to your artist before you go searching:
It is also a good idea to Google your artist and see what scholarly work and books you can find (there's a function that allows for this on google, just as there is a function that allows you to do image searches.) It is helpful to have a list of title from which to choose to look for before you go to the library. The more time you can save yourself, the more productive you will be.
Better than just "googling" blindly, you can go to newspaper and journal sites (besides the ones listed above.) You can be much more productive if you learn how to search the web. Here are some places you may want to look:
The New York Times
N.E. Journal of Aesthetic Research
Obviously the list could go on, and I didn't include any international papers, but you get the idea...or, you can do the leg work yourself!
Or find out where your artist has had a show and search the paper from that city.
Peace. & Good Luck.