You will need one of these books, and want the other one
The UPS guy showed up at my front door this afternoon bearing my book order from Scooterworks. Oh, joy!
If you’re going to own a PX, you are going to need the Haynes Vespa P-Series repair manual. The Haynes folks, unlike other publishers of third-party automotive repair manuals, acquire an example of the featured vehicle, pull it completely apart, put it back together again, and take tons of pictures in the process. Having had some rather obtuse service manuals for previous vehicles—“Widget Removal: Remove clevis bushing using special tool XFJ-3007-2B, remove widget. Installation is reverse of removal”—the Haynes approach is helpful and refreshing, and the manuals are considerably cheaper than the ones published by the manufacturers.
While perhaps not required, if you want to understand the whole scooter zeitgeist, Vroom with a View by Peter Moore is something you need to read, if for no other reason than people quoting it to you. The book revolves around Moore’s Italian road trip on a 1961 Vespa, a scooter that is the same age as the writer. One reader has compared the writing style of yours truly to Mr. Moore’s; I let you know what I think when I finish reading it.