| Value | Category | Cases | |
|---|---|---|---|
| 1 | Only when assignements are given | 17 | 
                                
                                9.1%
                             | 
| 2 | On request | 16 | 
                                
                                8.6%
                             | 
| 3 | Assigned the book without restrictions | 46 | 
                                
                                24.6%
                             | 
| 6 | Other | 7 | 
                                
                                3.7%
                             | 
| 9 | Not applicable | 101 | 
                                
                                54%
                             |