Device for binding sheets and bounded book

A device for binding sheets in a pack, the device having a flat rectangular sheet element (3) in turn having, along one major side (3a), a number of flexible tongues (7) arranged combfashion; and a closing strip (10) extending along the major side (3a). The strip (10) has an application surface (13) facing the tongues (7) and having a layer of adhesive (17). The flat element (3) is placeable on a first face of the pack, with the tongues (7) inserted inside the respective holes (33) formed along one edge of the pack, and with respective ends (7e) of the tongues (7) projecting from the holes. The closing strip (10) is foldable and placeable with the layer of adhesive (17) superimposed on a flat element (30b) defining a second face of the pack (30).