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, By the same means you can access Index to Legal Periodicals and Books Full Text
• Google Scholar: an alternative to Summon
  • info about using Scholar 
  • video intro to Scholar (3 mins)
• Nexis Uni: another major database with much legal material.

Other key resources:

• ethics and restitution guide for many more resources in that area
• IFAR: Art Law & Cultural Property for cultural property/ownership and export legislation for many countries
• Copyright Laws and Regulations 2021 is a guide to copyright in 24 jurisdictions, including the UK, USA, France, Germany, Russia, and a range of countries from all continents.