1 January 1990 - 1 January 1991
| DOI | https://doi.org/10.48597/6RTC-6DW4 |
|---|---|
| Start time | 1 January 1990 |
| Stop time | 1 January 1991 |
| DOI | https://doi.org/10.48597/GHD8-NC4H |
|---|---|
| Start time | 1 January 1989 |
| Stop time | 1 January 1990 |
| DOI | https://doi.org/10.48597/FCMH-6GEB |
|---|---|
| Start time | 1 January 1988 |
| Stop time | 1 January 1989 |
| DOI | https://doi.org/10.48597/XXGX-EATR |
|---|---|
| Start time | 1 January 1997 |
| Stop time | 1 January 1998 |
| DOI | https://doi.org/10.48597/FW6T-Z2T9 |
|---|---|
| Start time | 1 January 1987 |
| Stop time | 1 January 1988 |