A useful article for A Level Economics relating to protectionism / protectionist policies – http://www.bbc.co.uk/news/world-us-canada-43337951 
See where to find this section within the specs for Edexcel, AQA and OCR:-
Edexcel spec reference 4.1.6 Impact of protectionist policies on consumers, producers, governments, living standards, equality.
AQA spec reference 4.2.6.2 The causes and consequences of countries adopting protectionist policies. 
OCR spec reference P 25 Explain the impact of methods of protectionism to include a diagrammatic explanation of tariffs and quotas.
https://www.apt-initiatives.com/