I am rather certain these books are not for the Racca (Piano Melodico);
the size of the book doesn't match those I have seen in the past,
not even for the table model, as they seem too narrow (but I will check
this at home).  Furthermore, I have never come across a Racca book with
leather on the start/front piece.  Then again, it may be a rarity.

I think they look more like an organ book, something used for a small
street organ, looking at the size.

Ren
Renaissance Le Corbeau