| Value | Category | Cases | |
|---|---|---|---|
| 1 | Only when assignements are given | 10 | 
                                
                                4.7%
                             | 
| 2 | On request | 10 | 
                                
                                4.7%
                             | 
| 3 | Assigned the book without restrictions | 60 | 
                                
                                28.3%
                             | 
| 6 | Other | 4 | 
                                
                                1.9%
                             | 
| 9 | Not applicable | 128 | 
                                
                                60.4%
                             |