thank you for your suggestion. But I think (even if I didn't see Fernando Sor's Op.35 yet), that Sor's book does not teach how to play from a technical point of view.
What I'm looking for is a book that could replace a human teacher's (even if I know that it's not possible completely), i.e. a book that talks about the mistakes and how to avoid the mistakes done by the new guitarist, regarding body and finger positions, tips and tricks to learn the pieces, and so on.
From the other user's suggestions, I take it that one of the books satisfying my needs is Frederick Noad's, chich I still could not find in any shop near me.
Have a nice day!