Use the Catalog or I-Share search to find books (including e-books).
Information about your chosen artist may be available via the University Archives, if the artist had an affiliation with ISU (former faculty member, alumni, etc.).
A first step would be to search the archival finding aids (linked below) to see if anything comes up for your artist. If so (or if you want more assistance), call or email the Archives to talk with them about your research need, and to make an appointment to view the materials.
I-Share: A network of academic libraries in Illinois that share physical books and materials. If an item on Milner's website is in I-Share you'll see a list of the libraries that own it.
ILL (Interlibrary Loan): A network of many thousands of libraries across the United States (and beyond). Use ILL to get ahold of digital items such as articles that Milner does not have; as well as books that are not available via I-Share.