https://www.theguardian.com/books/2016/apr/24/robert-crumb-interview-art-and-beauty-exhibition
https://www.britannica.com/biography/R-Crumb
https://www.theparisreview.org/interviews/6017/r-crumb-the-art-of-comics-no-1-r-crumb
https://www.telegraph.co.uk/art/artists/robert-crumb-in-the-studio/