Device for holding together a stack of sheets

A device for holding together an end of a stack of sheets, wherein the device has a front and a back side, the device comprising:

• (a) a first wall on the back side of the device and a second wall on the front of the device, wherein
• (i) the first wall and the second wall are positioned in a substantially facing relationship to one another, wherein the first and second walls are joined together so as to define a space with a first opening at a first end of the space to receive the end of the stack of sheets, and a second opening at a second end of the space opposite the first end thereof;
• and wherein
• (ii) the first wall forms a first folding edge in the second opening, and wherein
• (iii) the second opening is adapted to allow the end of the stack of sheets to protrude over a predetermined distance in relation to the first folding edge when the stack of sheets resides in the space during operational use;
• and
• (b) an auxiliary piece which is pivotably attached to a rear side of the second wall near the second opening via a pivot point, wherein
• the auxiliary piece and the pivot point are configured and positioned in relation to the first folding edge such that, during operational use, the auxiliary piece is able to fold, the end of the stack of sheets about the first folding edge (E1) in a direction of a back side of the first wall via a lever arm effect acting on the end of the stack of sheets to achieve a folded state of the stack of sheets, and wherein
• the auxiliary piece is configured such that it protrudes, during operational use, in an unfolded state of the stack of sheets, at least at one location further than the end of the stack of sheets so that the auxiliary piece is able to make physical contact with the first wall in the folded state of the stack of sheets, and wherein
• the auxiliary piece is pivotably attached on the rear side of the second wall such that after folding the stack of sheets in the direction of the back side of the first wall, the front of the device defines a right angle to maintain a rectangular form of the sheets which the sheets had in the unfolded state thereof.