I have all these books and many more, so I have tried to give an appraisal of the ones worth having in 2020 though I avidly collected anything 928 related whenever published or found.

Porsche Chronicle

Buy from Amazon UK

Bargain colour printed book

Porsche 924, 928, 944, 968

Buy from Amazon UK

Important to the decision making process

Porsche 928 GTS

Buy from Amazon UK

70 pages of 928 GTS specifics

Porsche: Engineering for Excellence

Buy from Amazon UK

Autoritative 190 pages under a fiver!

Porsche 928, 1977-89

Buy from Amazon UK

Expensive reprints of magazine articles