The impact of syntax colouring on program comprehension (2015) [pdf]

The best book I know on subject of how to best display computer programs is:

Human Factors and Typography for More Readable Programs https://www.amazon.com/-/he/Ronald-M-Baecker/dp/0201107457

Related:

I am sorry, but everyone is getting syntax highlighting wrong

https://news.ycombinator.com/item?id=45596960