Shooting script of the film
http://www.raindance.co.uk/site/scripts/Trainspotting.pdf
This is a link to the script use to shoot the film. Not every scene ended up in the final version of the film, but it can help to follow the film and to understand which choices were made about what to cut.
Review and track listings of the soundtrack
https://www.allmusic.com/album/trainspotting-original-soundtrack-mw0000188788
This offers a review of the original soundtrack, and each track.
Official website of the film, via Miramax
https://www.miramax.com/movie/trainspotting/
This is the official website for the film and offers some general information
Original review in the Guardian
https://www.theguardian.com/film/News_Story/Critic_Review/Guardian_review/0,,530807,00.html
An early review of the film. It offers some useful analysis and opinions.
Interesting list of facts about the film
https://www.thesun.co.uk/archives/news/235843/20-things-you-probably-didnt-know-about-trainspotting/
This gives a list of 20 details about the film that have to do with its production or may have been hard to read from the film.