Tips for choosing exhibitions to research:
Not all exhibitions have catalogs! Usually, larger and well-resourced galleries and museums will publish printed catalogs.
Identify a few different exhibitions so that you have alternatives to fall back on if one or more of these does not have a catalog.
For information about older exhibitions (>20 yrs ago or more), you may have better luck in the library sources than Google.
To browse recent catalogs, try searching a specialty art bookstore / website. Artbook D.A.P. is one example.