The first version of the 964 released was the Carrera 4, as a demonstration of the leap forward in technology that would be offered by Porsche going forwards in the 911. Porsche incorporated technology and learning from the 959 supercar, including the four wheel drive system and aerodynamic bumpers.
964uk.com – A good starting point for research into the 964, including trouble shooting and DIY guides.
rennlist.com – Active forum with a great 964 community and history of topics that cover everything 964.
Porsche Passion – A great reference site that includes lists of colours and options as well as build numbers of each derivative.
964 30 Year Anniversary page – An owners page that lists the details of the 964 30 Year Anniversary model.