Which titles were directed by George Blair and written by Jackson Gillis?
CREATE TABLE "table1_15824796_3" (
  "series_num" real,
  "season_num" real,
  "title" text,
  "directed_by" text,
  "written_by" text,
  "original_air_date" text
);
SELECT "title" FROM "table1_15824796_3" WHERE "directed_by"='George Blair' AND "written_by"='Jackson Gillis';