I have been on the hunt for one of these for some time as the technical information provided within is second to none. These were originally produced for official use at VW approved garages and not available to the general public:
Worth the investment in my opinion and this will now serve as my main reference source for crucial measurements and certain repair procedures:
Just need to keep my eyes peeled for Vol 1 now… Edit 20/09/17: I managed to get my grubby mits on Vol 1! One came up for sale as an auction on eBay, but didn't attract many bidders so was mine at ludicrously low price. Got to love eBay, it is the classic car restorer's best friend!