If you can't find sufficient information in the library art databases, try these:
The Art Newspaper—after registering for an account, you can search for all sorts of interesting information about contemporary artists and the art market.
Nexis Uni—(an AU subscription database) has newspapers from all over.
Art gallery pages—Do you know the gallery that represents the artist? Sometimes gallery websites have interesting information.
Museum pages, including the the National Portrait Gallery
WorldCat—this is a database of books, but so many libraries contribute to it that you can find some obscure things.
ProQuest Dissertations and Theses (an AU subscription database.) Full text searching is available for many dissertations. The bibliographies/works cited lists are excellent.
Also take a look at the Art Subject Guides. To find all of our Subject Guides, go to the library's homepage under Research Assistance > Subject Guides.
