Provide a list of directors from the 1990s.
the 1990s refers to (cast(SUBSTR(release_date, instr(release_date, ', ') + 1) as int) between 1990 and 2000);
SELECT T2.director FROM movies_total_gross AS T1 INNER JOIN director AS T2 ON T1.movie_title = T2.name AND CAST(SUBSTR(release_date, INSTR(release_date, ', ') + 1) AS int) BETWEEN 1990 AND 2000 GROUP BY T2.director