Maximum Boost: Designing, Testing and Installing Turbocharger Systems - Corky Bell

I personally think this book is excellent, lots of technical detail as well as easy to read explanations of how turbo systems work.

Lancia Y10 - Piero Casucci

A small paperback book containing lots of information about the various Y10 models, at around £5 it is a must for any Y10 enthusiast.

Fuel Injection: Installation, Performance Tuning, Modification - Jeff Hartman

Another great book, I have found this very useful and has given me a much greater understanding of fuel injection, also covers use with turbocharged vehicles.