There are two kinds of parts books.
The smaller one that fits in the glovebox and the larger one that the dealers usually had.
The small one only shows the parts diagram with call out numbers.
The large one had the same parts diagrams but larger and the numbers calling out the various bits and a reference list of the parts numbers corresponding to the bits.
The small book is not so expensive, but the large one is expensive.
Sometimes you can find them on Fleabay(Ebay) or Facebook market place, or through MB sources.
Walter
1967 220SL diesel
1969 280SE
2003 Beetle TDI
2005 Honda Element