Summon is usually the best starting point for finding articles, books and dissertations. 

• video intro to Summon (4 mins) 
• collection of guides if you need help with particular Summon searches

You may also want to run supplementary searches in these databases:

•  EBSCO: includes  Business Source Premier. With a British Library reader's ticket you can access a more comprehensive business database: visit the British Library's electronic resources list, and search for Business Source Complete
• Google Scholar: an alternative to Summon
  • info about using Scholar 
  • video intro to Scholar (3 mins)

A basic search in Summon for material about art fairs:

If you are interested in a particular aspect of art fairs, search like this:

Using quote marks searches for the words as a phrase. Because using quote marks means the search is run very exactly, you will find a few more results like this:

To combine this with subject terms, use this punctuation:

You can of course search for material on specific fairs: