Found in 2 comments on Hacker News
parisidau · 2019-08-20 · Original thread
Shameless plug, I wrote a book on KSP (for O'Reilly!) with some friends: https://www.amazon.com/Kerbal-Players-Guide-Easiest-Program/...
parisidau · 2017-06-01 · Original thread
Shameless self-promotion, but together with some friends I wrote a book for O'Reilly Media on KSP!

Amazon: https://www.amazon.com/Kerbal-Players-Guide-Easiest-Program/...

O'Reilly: http://shop.oreilly.com/product/0636920035138.do

Safari: https://www.safaribooksonline.com/library/view/the-kerbal-pl...

Fresh book recommendations delivered straight to your inbox every Thursday.