Book
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a book with a plurality of sheets each comprising two leaves which are folded in the zone of the book back. 
     2. Description of the Prior Art 
     Books are known which consist of a plurality of leaves which are sown or glued together at the book back. The term &#34;book&#34; as stated hereinunder shall mean a product comprising a plurality of leaves connected to each other, which also includes booklets, brochures and the like. In known books it is often the case that two leaves form a sheet which is folded in the center. Often several such sheets are stuck within each other, so that the first and the last leaf of a book belong to one sheet, the second and one but last leaf belong to the next sheet and so forth. In order to ensure the cohesion it is necessary to either glue or sow them together. This is expensive and thus limits the possible number of pages in a book. It is possible that a book is compiled from several such partial books, but this solution is also very difficult to achieve. 
     From the German Patent 682 075 (SCHWENKE) a book is known whose pages are provided with laps which are inserted into respective cut-outs in the cover sheet. In order to ensure coherence, the laps have to be glued. 
     SUMMARY OF THE INVENTION 
     It is the object of the present invention to avoid such disadvantages and to create a book which requires no gluing or sowing and which can have an unlimited number of pages. 
     In accordance with the invention it is therefore provided that at least one sheet is provided whose one leaf is arranged between the two leaves of a further first sheet and whose second leaf is arranged between the two leaves of a second further sheet. The individual sheets interdigitate like the links of a chain. An additional connecting means is not necessary. 
     Preferably, a first group of sheets is provided, each comprising two cut-outs extending from two opposite edges towards the center of the sheet, and a further group of sheets is provided which comprises in the center a slot-shaped cut-out, each sheet of the first group being insertable into the cut-out of a respective sheet of the second group. When compiling the book, the sheet with the two cut-outs is folded and inserted into the center cut-out. 
     The production of a book in accordance with the invention is facilitated if a plurality of leaves of other sheets are arranged between the two leaves of a sheet. 
     An appealing arrangement is achieved if the two outermost leaves each belong to sheets of the second group with a cut-out in the center. 
     It is particularly advantageous if the cut-outs of the second group of the sheets have the shape of an elongated oval. The individual sheets center themselves by this measure. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The invention is now outlined in greater detail by reference to the enclosed drawings, in which: 
     FIG. 1 shows a sheet with two cut-outs; 
     FIG. 2 shows a sheet with a slot-shaped cut-out and 
     FIGS. 3 and 4 schematically show two embodiments of a book in accordance with the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The sheet 1 shown in FIG. 1 comprises two cut-outs 3 and 4 extending along the axis of symmetry 5 of sheet 1. The cut-outs 3 and 4 start in the center of the edges 6 and 7 of sheet 1 and have lengths l 1  and l 2 . The axis of symmetry 5 divides sheet 1 into leaves 1&#39; and 1&#34;. 
     The sheet 2 shown in FIG. 2 comprises a slot-shaped cut-out 8 extending along the axis of symmetry 9. The cut-out 8 has a substantially oval shape and a length l 3 . The total of lengths l 1  and l 2  of cut-outs 3 and 4 and the length l 3  of the slot-shaped cut-out 8 has to be equal to or slightly greater than the length L of the edges 10 or 11 of sheets 1 or 2 which are parallel to the axis of symmetry 5 or 9. The axis of symmetry 9 divides the sheet 2 into leaves 2&#39; and 2&#34;. 
     FIG. 3 shows the minimum arrangement of a book in accordance with the invention. A sheet 1a, folded along the axis of symmetry 5 shown in a broken line, holds the sheets 2a and 2b extending respectively along leaves 1a&#39; and 1a&#34; of sheet 1a. Leaf 1a&#39; is inserted between the leaves 2a&#39; and 2a&#34; of sheet 2a and the leaf 1a&#34; of sheet 1a is inserted between the leaves 2b&#39; and 2b&#34; of sheet 2b. 
     FIG. 4 shows the manner in which it is possible to produce a book of arbitrary thickness. The leaves 1c&#39; and 1d&#39; of sheets 1c and 1d are arranged between the leaves 2c&#39; and 2c&#34; of sheet 2c. The leaves 1c&#34;, 1d&#34;, 1e&#39; and 1f&#39; of sheets 1c, 1d, 1e, 1f are arranged between the leaves 2d&#39; and 2d&#34; of sheets 2d. Finally, the leaves 1e&#34; and 1f&#34; of sheets 1e and 1f are arranged between the sheets 2e&#39; and 2e&#34; of sheet 2e. 
     It is clear that the present invention is not limited to books, booklets and the like with rectangular leaves of even size.