1 January 1990 - 1 January 1991
| DOI | https://doi.org/10.48597/Z2X8-59EN |
|---|---|
| Start time | 1 January 1990 |
| Stop time | 1 January 1991 |
| DOI | https://doi.org/10.48597/49DV-2GA9 |
|---|---|
| Start time | 1 January 1989 |
| Stop time | 1 January 1990 |
| DOI | https://doi.org/10.48597/WHME-49ME |
|---|---|
| Start time | 1 January 1988 |
| Stop time | 1 January 1989 |
| DOI | https://doi.org/10.48597/U5CA-RHS5 |
|---|---|
| Start time | 1 January 1997 |
| Stop time | 1 January 1998 |
| DOI | https://doi.org/10.48597/N9N9-H8WJ |
|---|---|
| Start time | 1 January 1987 |
| Stop time | 1 January 1988 |