A customs union explained

Thanks to the BBC
https://www.bbc.co.uk/news/av/uk-46195799/reality-check-the-customs-union-explained

The joy of a customs union

https://www.bbc.co.uk/news/av/business-45590363/from-belgium-to-the-uk-the-journey-of-an-alloy-wheel

Brexit: Different policies on the single market and customs union

Interesting post from the BBC
http://www.bbc.co.uk/news/av/uk-politics-43332832/brexit-different-policies-on-the-single-market-and-customs-union

Customs Union – advantages and disadvantages

Thanks to economicshelp
https://www.economicshelp.org/blog/138713/economics/customs-union/

Free trade area, single market, customs union - what's the difference?

Thanks to the BBC
http://www.bbc.co.uk/news/business-36083664

Brexit: What is the EU customs union and why should people care that the UK is leaving it?

A nice summary from the Independent
http://www.independent.co.uk/news/business/news/brexit-latest-news-what-is-eu-customs-union-why-care-if-uk-leaves-it-european-union-deal-a7529361.html

What is a customs union?

Thanks to the BBC
http://www.bbc.co.uk/news/uk-36906796