1 January 1990 - 1 January 1991
| DOI | https://doi.org/10.48597/5AWZ-2HUX |
|---|---|
| Start time | 1 January 1990 |
| Stop time | 1 January 1991 |
| DOI | https://doi.org/10.48597/SJEH-WP97 |
|---|---|
| Start time | 1 January 1989 |
| Stop time | 1 January 1990 |
| DOI | https://doi.org/10.48597/NNRH-9UCM |
|---|---|
| Start time | 1 January 1988 |
| Stop time | 1 January 1989 |
| DOI | https://doi.org/10.48597/2V4C-M5WB |
|---|---|
| Start time | 1 January 1997 |
| Stop time | 1 January 1998 |
| DOI | https://doi.org/10.48597/NWJP-46RV |
|---|---|
| Start time | 1 January 1987 |
| Stop time | 1 January 1988 |