Who is the director for the series # 39?
CREATE TABLE "table1_26968451_2" (
  "series_num" real,
  "season_num" real,
  "title" text,
  "directed_by" text,
  "written_by" text,
  "original_airdate" text
);
SELECT "directed_by" FROM "table1_26968451_2" WHERE "series_num"=39;