If you're interested in some Toyota rally history, this is a good starter book (I'm sure you can find a hard copy somewhere online; it's only in Kindle form on Amazon now). It's comprehensive enough to delve a bit deep into the technical side of the car, yet general enough to give you an understanding of development of Toyota's first true WRC contender.

The only real quibble I have is that the author, Graham Robson, has a bit too much of a hard-on for 2-time WRC champion Carlos Sainz but writes off 4-time WRC champion Juha Kankunna as very talented but lazy. Seriously, he only has couple of paragraphs on Kankunna (in a less than flattering light) while giving Sainz a comparative hagiography.

https://www.amazon.com/Toyota-Celica.../dp/B00WGTA6W0

To be honest, I only bought the book because it was going for $3 on Amazon at the time. I was already buying a Robson book on my favorite WRC car of all time, the Peugeot 205 T16, so I figured why not? I don't regret the purchase one bit.