| GRPE/2019/12 | GTR 2: Proposal for Amendment 4 | |
| GRPE-79-21/Rev.1 | GTR 2: Consolidated text incorporating Amendment 4 | |
| GRPE-79-22 | GTR 2: Technical report on the development of Amendment 4 | |
| GRPE-79-23 | GTR 18: Consolidated draft amendment to introduce OBD2 | |
| GRPE/79/Add.1 | GTR 2: Amendment 4 as approved by GRPE | |
| GRPE/2019/12 | GTR 2: Proposal for Amendment 4 | |
| GRPE-79-22 | GTR 2: Technical report on the development of Amendment 4 | |
| GRPE/2019/12 | GTR 2: Proposal for Amendment 4 |