Manuals are just that-- manuals. These PDF's are the collection of materials I've gathered over the years from various sources. Most (if not all) are long since out of print, and have expired out of copyright. I've purchased the majority from literature resellers out there on eBay-- they comb through estate sales, closed dealerships, defunct repair shops and the like finding these little treasures. Those of you with the "disease" know the names like AutoLit, PaperHeaven, NuttyBuick, etc... I've spent a fortune on those guys-- but frankly they seem to find the rarest of the rare when it comes to literature.
I personally think it very important to digitally capture all of these manuals for future reference because (unfortunately) craftsman who know how to work on our cars are a rapidly dwindling population. I cannot tell you the number of times I've called up a local shop to ask for help with my Buick, only to have the person on the other end of the line ask "Uh... what year did you say? 1956? Sorry, can't help you.". Nowadays, I ask the shop first "You have anyone in your shop that can work on old cars?" first, and then go from there. Sometimes they'll refer you out to other shops where they know the old timers (or the old timer's son/daughter) can handle the request competently.