Buy from Amazon UK

Extremely cheap good book

Porsche - The Legend

Don't be put off. Colour pictures of all models and some good detail with tables a little bit like a top trumps deck of information.

928 model coverage is good with pictures of UK cars from 1979, 1988 and 1995 although the author dismisses the 928 as a footnote in the companys evolution.
For a couple of quid its worth adding to your collection.

Jonathan Wood Porsche - The Legend