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.