In addition I'd also recommend "Casting the Net" by Peter H Salus:
https://www.amazon.co.uk/Casting-Net-ARPANET-INTERNET-System...
I have both books (each now over 20 years old), but I think "Casting the Net" is a slightly more rigorous and somewhat less "journalisty" history with a better collection of diagrams and scribbles by the key figures involved.