Wayne, Artyczar, glad you liked it.
Wayne thank you very much, yes on the books I think they call it hatching, it's a kind of shading that I really like, even though in the early years I actually liked to see hatching drawings but never do them, almost never, because I wanted to learn normal shading first, to be able to do it smoother and spotless, then I thought not to postpone hatching anymore because I would probably postpone this too forever.
I have a little book by Civardi, it is more about theory, chiaroscuro theory (this is also the title and I have to reread it, I think I'll come back soon, to grasp it better and not forget), but it has style and therefore examples of his works that are very beautiful.