| UN R21: Revision 2-Corrigendum 1 (2000) |
| Revision 2 | Amendment 1 (1998) |
| Revision 2 | Amendment 2 (2003) |
| Revision 2 | Amendment 3 (2020) |
| Revision 2 | Part 2 (1993) |
| Revision 2 | Part 1 (1993) |
| Earlier texts may be available through the UN Official Document System. |