Last week SNP leader Nicola Sturgeon wrote to Theresa May to request a second independence referendum for Scotland
The Scottish government has an official video
and the parliamentary website provides details of the Scottish Parliament vote in favour of the referendum.
you can can read the full text of the speech from 13th March when Ms Sturgeon called for a second referendum in the face of 'hard brexit'
The Scottish website has background on the call for the referendum
this includes details of the consultation on a draft referendum bill which closed in January 2017
Fullfact has considered whether Scotland can legally hold another referendum
Good discussion can also been found on the UK Constitutional Law Blog
Good sources for recent comment
What Scotland thinks. It also includes excellent analysis from expert John Curtice.
ScotCen - published a recent survey on what Scottish voters think of the independence voting.
Research discussion- the Conversation blog.